Suggested Searches

PP&C Glossary

The NASA Cost Estimating & Analysis, Schedule Management, and EVM communities worked together to create a comprehensive Glossary of PP&C terms.

A  |  B  |  C  |  D  |  E  |  F  |  G  |  H  |  I  |  J  |  K  |  L  |  M  |  N  |  O  |  P  |  Q  |  R  |  S  |  T  |  U  |  V  |  W 

A

Acceleration (Compression) – Schedule acceleration, or compression, is a group of techniques used to minimize the duration of work included into the Program or project in order to:

  • Reduce a delay that will impact project performance to a level within tolerance threshold
  • Complete schedule activities faster than originally planned
  • Stay on schedule although previous critical activities were delayed

In accelerating the schedule, more work will be performed in the original time estimated, the same scope of work will be performed in less time, or there may be a combination of both.  Two common schedule acceleration techniques include Crashing and Fast Tracking.

Activity (Task) – A defined element of work in the schedule, which has an expected duration, an expected cost, and expected resource requirements.  An activity is the lowest level of detail shown in an Integrated Master Schedule (IMS). 

Activity Attributes – Details of Program or project activities, which are used to help Program or project planning and scheduling (e.g., Activity ID, WBS No., Activity Description, Predecessors, Successors, etc.).  Activity attributes are typically captured and logged either manually via a standard form or template or entered into the Program or project scheduling software.

Activity Duration – See Duration.

Activity Owner – The individual responsible for executing an activity.  The Activity Owner may be a Technical Lead, WBS Element Owner, Control Account Manager (CAM), Integrated Product Team (IPT) Lead) or other Program or project -assigned individual.  The Activity Owner has the assigned responsibility of accomplishing the work contained in each WBS element to comply with the Schedule Management Plan.

Actual Cost (AC) – See Actual Cost of Work Performed (ACWP)

Actual Cost of Work Performed (ACWP) – The costs actually incurred and recorded in accomplishing the work performed within a given time period. Actual costs include the direct costs plus the related indirect cost such as overhead, general, and administrative, etc. allocated to the activity. ACWP reflects the applied direct costs and may be for a specific period or cumulative to date. (Also known as Actual Cost). 

Acquisition – Obtaining or advancing the development of the systems, research, services, construction, and supplies to fulfill the Agency’s mission and other activities which advance the Agency’s statutory objectives.

Acquisition Strategy – The plan or approach for using NASA’s acquisition authorities to achieve the mission of a project. It includes the recommendations from make/buy analyses, the recommendations from competed/directed analyses, proposed partnerships and contributions, proposed infrastructure use and needs, budget, and any other applicable considerations. 

Acquisition Strategy Meeting (ASM) – A decision-making forum where senior Agency management reviews and approves project acquisition strategies. The ASM focuses on considerations such as impacting the Agency workforce, maintaining core capabilities, make-or-buy decisions, supporting Center assignments, potential partnerships, and risk. 

Administrative Contracting Officer (ACO) – The individual within the Defense Contract Management Agency (DCMA) Contract Management Office (CMO) responsible for ensuring that the functions described in NFS 1842.302 are completed by the contractor in accordance with the terms and conditions of the contract. 

Advance Agreement (AA) – The agreement between the Administrative Contracting Officer (ACO) and the contractor that documents the contractor’s commitment to use the accepted Earned Value Management System (EVMS) as an integral management process on current and future contracts and maintain the EVMS compliant system through an internal surveillance program. 

Agency Baseline Commitment (ABC) –  Establishes and documents an integrated set of project requirements, cost, schedule, technical content, and an agreed-to JCL that forms the basis for NASA’s commitment to the external entities of OMB and Congress.  Only one official baseline exists for a NASA P/p, and it is the Agency Baseline Commitment.

Actual Finish Date – The actual date the activity completed.  See also Finish Date

Actual Start Date – The actual date the activity started.  See also Start Date

Analogous Estimating – A top-down estimating technique that uses the historical information from previously performed activities that are similar in nature to estimate the effort, duration, or cost needed to complete an activity; Analogous estimates are often adjusted for differences in complexity.  See also Schedule Estimate and Top-Down Estimating.

Analogy – A currently fielded system (comparable system) similar in design and/or operation of the proposed system. The cost of the proposed system is developed by taking the fielded system’s data and adjusting them to account for any differences. Analogous estimates are also called comparative or extrapolated estimates. (CEH)

Analysis of Alternatives (AoA) – A formal analysis method that compares alternative approaches by estimating their ability to satisfy mission requirements through an effectiveness analysis and by estimating their life cycle costs through cost analysis. The results of these two analyses are used together to produce a cost-effectiveness comparison that allows decision makers to assess the relative value or potential programmatic returns of the alternatives. An analysis of alternatives broadly examines multiple elements of project alternatives (including technical performance, risk, LCC, and programmatic aspects). 

Analysis Schedule – A representation of the IMS that summarizes the work at an appropriate level to reflect the potential impact of uncertainties and/or risks for use in a modeling and simulation environment, such as for an SRA or ICSRA.  It is not the same as a Summary Schedule that uses an across-the-board roll-up approach, instead summarizing WBS elements at different levels according to the need to model uncertainties and risks in particular areas of the schedule.  An Analysis Schedule should reflect the appropriate level of fidelity, such that it is directly traceable to the IMS, replicates the critical paths, and emulates the IMS under the influence of risks and uncertainties.  If used for an ICSRA, the Analysis Schedule may also include Hammock Activities to model costs at a summary level. The analysis schedule should be examined and accepted by the owner, contractor and other stakeholders if needed, as a representation at a level above the detailed schedule.

Announcement of Opportunity (AO) – A mechanism used to solicit proposals for unique, high-cost research investigation opportunities that typically involve flying experimental hardware provided by the bidder on one of NASA’s Earth-orbiting or free-flying space flight missions. Scope selection through AOs can require development periods of many years and involve budgets of many millions of dollars for the largest programs. Selections are usually awarded through contracts, even for nonprofit organizations, although occasionally grants are also used. (CEH)

Apportioned Effort – Activity effort that is related in direct proportion to measured effort and is not readily measurable or broken into discrete work packages.  See also Activity.

Assumption – A factor that is uncertain, but for schedule management purposes is considered to be true, real, or certain.  An assumption should also describe the potential impact of the factor if it proves to be false.  For Schedule Management, assumptions are generally documented in the Schedule Management Plan (SMP) and as part of the schedule Basis of Estimate (BOE).

Authorized Unpriced Work (AUW) – Any effort for which contractually definitized costs have not been agreed upon, but for which written authorization has been received.

Return to Top

B

Backward Pass – A calculation used by the scheduling software tool that subtracts durations from late finish dates to determine the latest possible start and finish dates for every activity in the schedule network.

Base Calendar – Defines the standard working period for all of the Program or project activities.  It is the default calendar for the Program or project.  See also Calendars.

Baseline – The technical performance and content, technology application, schedule milestones, and budget (including Unallocated Future Expenses (UFEs)) that are documented in the approved Program or project plans. 

Baseline Change Request (BCR) – A request for changes to the established baselines in whatever form they may appear throughout the life cycle.  A BCR is often made with a standard form/template used to document and justify a proposed change to either the Estimate-at-Complete (EAC) or the Performance Measurement Baseline (PMB).

Baseline Execution Index (BEI) – A schedule-based metric that calculates the efficiency with which activities have been accomplished when measured against the baseline activity completion dates.  It is the ratio of the total number of tasks that should be complete through the Program or project status date (according to the baseline finish date) versus the total number of activities that have actually completed.  Calculation:  BEI = # of planned tasks (per baseline) actually completed on or before IMS status date / # of tasks planned (per baseline) to complete on or before IMS status date. 

Baseline Schedule – The original, approved Program or project schedule plan plus or minus approved scope changes that serves as the basis for performance and progress measurement during Program or project implementation.

Basis of Estimate (BOE) – The documentation of the ground rules, assumptions, and drivers used in developing the cost and schedule estimates including applicable model inputs, rational or justification for analogies, and details supporting cost and schedule estimates. 

Beta Curve – A method that can be used for spreading parametrically derived cost estimates. The Beta Curve’s shape can be tailored by modifying two parameters: cost fraction and peakedness.

Bottom-Up Estimating – An estimating technique that requires detailed, historical information in relation to Program or project characteristics.  It usually includes decomposing activities into smaller components, then individually estimating these components of work.  The smaller components are then aggregated to develop the estimate for the activity.  Bottom-up estimating is more time consuming and typically requires more Program or project staff involvement, but it generally produces more refined estimates.  Types of bottom-up estimating techniques include:  Detailed/Grassroots Estimating, Brainstorm Estimating, and Probabilistic Estimating.  See also Schedule Estimate.

Brainstorm Estimating – A bottom-up technique for estimating schedule durations that allows Program or project team members to approximate durations based on a combination of other estimating techniques/factors (e.g., expert judgment, prior experience, and historic actuals).  See also Schedule Estimate and Bottom-Up Estimating.

Budget – A financial plan that provides a format estimate of future revenues and obligations for a definite period of time for approved programs, projects, and activities.

Budget at Completion (BAC) – The sum of all budgets (BCWS) allocated to the project or a given Control Account.

Budgeted Cost for Work Performed (BCWP) – The sum of budgets for completed work packages and partially completed work packages, plus the appropriate portion of the budgets for level of effort and apportioned effort work packages. (Also known as Earned Value).

Budgeted Cost for Work Scheduled (BCWS) – The sum of the budgets for all work packages, planning packages, etc., scheduled to be accomplished (including in-process work packages), plus the amount of level of effort and apportioned effort scheduled to be accomplished within a given time period. This is the value of planned work. (Also known as Planned Value).

Budget-Loaded Schedule – A schedule whereby budgeted dollars are mapped to schedule activities to reflect the complete Program or project budget.  See also Budget Loading.

Budget Loading – The process of assigning budgeted dollars (not estimated costs) as the only resource to a schedule activity or a group of activities.  Because the budget does not reflect the expected costs of Program or project (e.g., historical resource costs/cost trends, risks and uncertainties that can cause schedule delays resulting in increased costs, etc.), budget loading may underestimate projected costs and ultimately not provide a credible confidence level through ICSRA/JCL analysis.  See also Budget-Loaded Schedule.

Buffer – Margin-like activities, or blocks of time within the schedule (working days), that are strategically placed in the schedule to safeguard or “buffer” critical or high-risk activities or key events that are not located on the primary critical path.  Buffers are typically placed on near-critical paths or probabilistic critical paths that have associated risks, so that these paths do not overtake the schedule and become the primary critical path.  Note:  These activities must be deleted before conducting a Monte Carlo simulation to determine the proper overall contingency of time, since these activities do not represent the estimate of how long the work is estimated to take but they will persist in the simulation, perhaps leading to overestimating of total project schedule risk.

Business Case Analysis (BCA) – A method to aid decision makers in the comparison of alternative approaches, options, or projects. A BCA considers not only all LCCs identified by a Life Cycle Cost Estimate (LCCE), but also other quantifiable and nonquantifiable benefits for all possible alternatives. 

Return to Top

C

Calendar – The area in the scheduling tool where the work hours/non-work hours and work days/non-work days are defined for the Program or project.  Calendars may be different for each organization, contractor, or resource working for the Program or project; those differences must be noted and calendars labeled to provide a clear distinction.  Two main types of schedule calendars include the Base Calendars and Modified Base Calendar(s).  See also Resource Calendar.

Change Control – A systematic approach to managing changes to the Program or project schedule.

Change Control Board (CCB) – The CCB is a committee that makes decisions on whether proposed changes to project baselines (technical, schedule or cost) should be accepted. 

Change Request (CR) – A request submitted to the CM/DM function to approve an initial release or a change to an item under configuration control.  See also Baseline Change Request.

Coefficient of Determination (R2) – In the context of statistical models, this is the proportion of variability in a dataset accounted for by the statistical model. In cost estimating, it provides a measure of how well cost estimates are likely to be predicted by the model. R2 ranges between 0 (no relationship) and 1 (perfect relationship). 

Coefficient of Variation (CV) – A normalized measure of the dispersion of a probability distribution. The absolute value of the CV is sometimes known as relative standard deviation (RSD), which is expressed as a percentage. 

Commercial Off The Shelf (COTS) – A term usually used to describe purchased software (as opposed to customized or internally developed software).

Completion Range (Range Estimate) – A high and a low confidence level range estimate for the Program or project schedule completion date (or other pre-determined milestone).  Two primary methods for determining the completion range include parametric estimating or schedule risk analysis (SRA) performed on the schedule estimate.  Completion Ranges can also be developed for Program or project costs using parametric estimating or integrated cost and schedule risk analysis (ICSRA/JCL).

Compliance – The characteristic of an EVMS that ensures the intent of the EVMS Guidelines is embodied in the integrated processes and sub processes of a organization’s methods of operation that generate accurate and auditable program performance data.

Compounding – The process of going from today’s values, or present values (PVs), to future values (FVs). 

Compression – See Acceleration.

Conditional Branching – An analysis technique through which an activity in the schedule is selected to occur given a condition defined by the analyst as a schedule event that may or may not occur on any iteration in the simulation.  A conditional branch is typically structured as follows:  IF [Condition] = TRUE, THEN execute branch activities.  Conditional branching may allow for changes in activity durations, changes in schedule logic, and/or changes in constraints.  A common use of this capability is to program a “Plan B” that will only occur if some activity, say detailed engineering, is much later than planned, where plan B may entail the addition of resources to the building phase to try to recover schedule.  Conditional branching may be used for Analysis of Alternatives or in Schedule Risk Analysis.  See also Probabilistic Branching.

Confidence Level (CL) – A statistical measure of the reliability of the Program or project schedule.  It provides the likelihood (%) that a Program or project will achieve its objectives on time.  It is a condition in which there is the probability that a given Program or project’s schedule will be equal to or less than the targeted schedule for completion.

Configuration Management/Data Management (CM/DM) – An external function that is responsible for providing control of documentation, data, and technical characteristics of both configuration and non-configuration products for a Program or project.  As applied to programmatic work products, CM/DM is responsible for providing visibility into and controlling changes to performance, functionality, and physical characteristics and requirements.  It is the backbone of Schedule Documentation and Communication and facilitates the capture, archive, and dissemination of information throughout the Program or project life cycle, while maintaining the integrity and protection of data

Consequence – Severity of performance degradation that would result if a risk scenario were to occur.  With respect to schedule, the impact is the effect on the durations of activities if the risk happens.  Consequence is one of two dimensions to risk; the other is Likelihood of the risk occurring.  Also referred to as Impact.  See also Uncertainty and Risk.

Constant Year (CY) Dollars – An analytical technique that translates a Real Year (RY) dollar estimate (the year expenses were realized) to a single-year value by discounting the effects of inflation. A figure expressed in CY dollars reflects the present value of a single year. Cost models are developed by the normalization of actual costs to remove the effects of inflation from historical data points, which are used to develop the model.  Cost estimating results are thus produced informed CY values. 

Constraint – Any external factor that limits the ability to plan with certainty.  The most common constraints are scope, time, and cost but they could be any factor such as law, weather or resource availability. Constraints and assumptions are often closely linked.  See also Date Constraint

Consumables – The resources that have a specified quantity, and when used up, must be replaced (e.g., fuel, steel, cabling, etc.).  See also Resource.

Contingency – Non-working days in the schedule (such as holidays or weekends) that could be used to overcome performance delays.  (Note:  Contingency is not to be confused with margin/working-days that are used to overcome uncertainties and risks.)

Contract – A mutually binding legal relationship obligating the seller to furnish the supplies or services (including construction) and the buyer to pay for them. It includes all types of commitments that obligate the Government to an expenditure of appropriated funds and that, except as otherwise authorized, are in writing. In addition to bilateral instruments, contracts include (but are not limited t) awards and notices of awards; job orders or task letters issued under basic ordering agreements; letter contracts; orders such as POs under which the contract becomes effective by written acceptance or performance; and bilateral contract modification. Contracts do not include grants and cooperative agreements. 

Contract Budget Base (CBB) – The sum of the negotiated contract cost plus the estimated cost of authorized unpriced work. It includes the PMB and MR. Customer approval is generally required to change it. (See also Project Budget Base.

Contracting Officer (CO) – A person with the authority to enter into, administer, and/or terminate contracts and make related determinations and findings.

Contracting Officer’s Technical Representative (COTR) – A person responsible to the CO for the contractor’s performance on a given contract.

Contract Performance Report (CPR) – A contract data requirement when EVM is required. This report consists of five formats containing data for measuring contractors’ cost and schedule performance on Government acquisition contracts: Format 1 provides data to measure cost and schedule performance by product-oriented WBS elements, the hardware, software, and services the Government is buying. Format 2 provides the same data by the contractor’s organization (functional or Integrated Product Team (IPT) structure).  Format 3 provides the budget baseline plan against which performance is measured.  Format 4 provides staffing forecasts for correlation with the budget plan and cost estimates.  Format 5 is a narrative report used to explain significant cost and schedule variances and other identified contract problems and topics. (See Integrated Program Management Report (IPMR) See Integrated Program Management Report (IPMR).

Contract Work Breakdown Structure (CWBS) – A work breakdown structure of the products or services to be furnished under contract. It is comprised of selected Project WBS elements specified in the contractual document and the contractor’s lower level extensions of those elements. 

Control Account – An identified intersection of the Work Breakdown Structure (WBS) and Organizational Breakdown Structure (OBS) at which responsibility for work is assigned to one organizational unit and actual direct labor, material, and other direct costs (ODC) are compared with the planned budget and the earned value for management control. 

Control Account Manager (CAM) –  See Project Control Account Manager (P CAM).

Control Account Plan (CAP) – A format upon which a control account plan is displayed. A CAP typically displays the control account scope and budget in time-phased work packages and planning packages, cost element visibility, earned value techniques for each work package, responsible performing organizations and at least one charge number. 

Control Milestone – Milestones owned by the sponsors or the stakeholders and cannot be changed by the Program or project.  See also Milestone and Notification Milestones.

Corrective Actions – Formal actions taken by the Program or project to correct poor performance, such as violation of pre-determined Program or project control thresholds.  Corrective actions are tracked by the Program or project through the CM/DM process.

Corrective Action Plan (CAP– Documents action(s) required to resolve deficiencies. 

Corrective Action Request (CAR) – Documents deficiencies that require corrective action. 

Correlation – A statistical technique used to determine the degree to which variables are related or associated. Correlation does not prove or disprove a cause-and-effect relationship.

Cost Analysis Data Requirement (CADRe) – A 3 part document endorsed by a project for tightly coupled and single-project programs (regardless of Category or Class) with an estimated life-cycle cost greater than $50 million that provides critical data to assist NASA in developing high fidelity cost and schedule estimates for new NASA projects.  CADRe consists of Part A “Narrative” and Part B “Technical Data” in tabular form, provided by project using existing project material. The project team produces the project lifecycle cost estimate, schedule, and risk identification which is appended as Part C. Projects shall provide a Cost Analysis Data Requirement (CADRe) baseline for SDR with updates for PDR, CDR, SIR, MRR/FRR and DR.

Cost As an Independent Variable (CAIV) – The process of examining cost drivers by holding cost independent of other technical parameters. CAIV is founded upon two primary principles: first, system costs are constrained; and second, “trade space” is the foundation for smart decisions. Trade space is the range of alternatives available to decision makers. It is four-dimensional, comprising performance, cost, schedule, and risk impacts. 

Cost Benefit Analysis (CBA) – An analytic technique that compares the costs and benefits of investments, programs, or policy actions in order to determine which alternative(s) maximize net profits. Net benefits of an alternative are determined by subtracting the present value of costs from the present value of benefits. Guidance for Cost Benefit Analysis for Government programs is provided in OMB Circular A-94. 

Cost Breakdown Structure (CBS) – A preliminary Work Breakdown Structure (WBS) produced by a cost estimator to facilitate the generation of a cost estimate prior to the development of a project WBS. The CBS should be consistent with the NASA standard Level 2 WBS. 

Cost Driver – Input variables for a cost estimating model that will have a significant effect on the cost estimate. 

Cost Estimate – The result of applying quantitative techniques to calculate and forecast development, production, operation, and disposal costs within a scheduled timeframe and defined scope for a given project. 

Cost Estimating Relationship (CER) – A mathematical relationship that defines cost as a function of one or more independent parameters such as performance, operating characteristics, or physical characteristics. 

Cost-Loaded Schedule – A schedule whereby cost estimates, including TI and TD costs, are mapped to schedule activities to reflect the complete Program or project cost.  See also Cost Loading, Resource-Loaded Schedule, and Resource Loading.

Cost Loading – The process of assigning projected costs (in dollars) as the only resource to a schedule activity or a group of activities for the purposes of estimating Program or project duration, cost, feasibility, workforce planning, and ICSRA/JCL analysis.  See also Cost-Loaded Schedule.

Cost Performance Index (CPI) – A measure of cost efficiency. It compares BCWP to the actual cost to perform that work (CPI = BCWP / ACWP). An index of 1.0 means that we are spending exactly what we planned to spend to accomplish the work performed. CPI > 1.0 means we are under running costs. CPI < 1.0 means that we are over running costs.

Cost Risk – Risk due to statistical uncertainty in the cost estimating methodology, technical parameters, economic factors, rates, and schedule, as well as programmatic and technological factors. (CEH)

Cost Variance (CV) – A metric for the cost performance derived from earned value data. It is the algebraic difference between earned value and actual cost (CV = BCWP – ACWP). A positive value indicates a favorable condition and a negative value indicates an unfavorable condition. It may be expressed as a value for a specific period of time or cumulative to date. (EVM)

Crashing – A schedule acceleration technique whereby resources are added or longer work days are approved to perform the work in a shorter period of time, thereby accelerating the overall schedule duration.  See also Acceleration.

Credibility – A property of the Program or project schedule that indicates it is trusted and reliable.  Schedule credibility is tested through the Analogy Test and Structural Tests as part of Schedule Assessment.  See also Integrity, Validity, and Quality.

Critical Activity – Any task that may or may not be on the critical path but has been identified by management to be given this distinction due to the inherently “risky” or “uncertain” nature of the task.  Critical activities may be defined as any tasks which have been deemed important enough to have this distinction assigned to them.  For example, key decision points, the development of a primary system component, or important tests may be considered “critical activities.”  Critical Activities should not be confused with Critical Path Activities, which are “schedule critical.”

Critical Path (Deterministic) – A sequential path of activities in a network logic schedule that represents the longest overall duration from the status date through Program or project(P/p) completion, which determines the shortest possible P/p duration (i.e., least amount of float) and earliest possible P/p finish date.  Any slippage of the tasks in the critical path will increase the P/p duration and slip the P/p finish date.  Also referred to as the primary critical path.  The critical path in the schedule is determined using the deterministic dates. Also referred to as the “primary critical path”.  Other instances of a “critical path”, which usually have different definitions, include:  Near Critical PathStochastic Critical PathDriving PathNear-Driving Path, and Status Date

Critical Path Activity – Any activity on the primary critical path.  See also Critical Path.

Critical Path Length Index (CPLI) – The CPLI is a measure of the efficiency required to complete a schedule milestone on time.  The CPLI measures the ratio of the remaining critical path length plus the total float to the remaining critical path length.  Calculation:  CPLI = (Critical Path Length + Total Float) / Critical Path Length.

Critical Path Method (CPM) – A logic network diagram scheduling technique used to estimate the minimum Program or project duration by calculating the longest path through the schedule logic network and to determine the amount of flexibility in each of the logic network paths. 

Cumulative Distribution Function (CDF) – A function that describes the probability that a real-valued random variable, X, with a given probability distribution will be found at a value less than or equal to x.  In SRA practice, the CDF or “S-Curve” is used to identify the date to choose as the target that has an acceptable probability of being exceeded.  For instance, the P-70 value has only a 30% likelihood of further slipping.  The accuracy of this date depends on the project schedule and the risks / uncertainty used in the modeling of schedule risks.  CDFs are used to specify the distribution of multivariate random variables.  CDFs are also known as Sigmoid functions (S-Curves).

Current Execution Index (CEI) – An IMS-based metric that calculates the efficiency with which tasks have been accomplished when measured against the previous period forecasted completion dates.  Calculation:  CEI = # of forecasted activities that were actually completed on or before IMS status date / # of forecasted tasks to complete on or before IMS status date.

Return to Top

D

Dangling Activity – An activity that does not have a successor (F-S or F-F) from its finish date or a predecessor (F-S or S-S) to its start date.  Repairing this logical error before analysis and/or simulation is important to count on the accuracy of the results.  Also referred to as Open Ends.

Dangling Logic – Schedule logic that is not properly tied to an activity’s start or end date.  Also referred to as Hanging Logic. See also Dangling Activity.

Data Requirements (DR) – A set of data required for supplier/contract management and reporting.

Data Requirements Deliverables (DRD) – The document that describes the specific data required for supplier/contract management and reporting.

Date Constraint – A date restriction assigned to an activity or milestone to control when it starts or finishes.  Constraints and assumptions are often closely linked.  Constraints fall into two main categories that include Hard Constraints and Soft Constraints.  Some software tools also include Deadlines, which are similar to Hard Constraints but do not compromise schedule logic.  See also Deadlines, Hard Constraints, and Soft Constraints.  (Note:  Constraints override logic relationships.)  

Deadline – (MS Project only) While not specifically a constraint type, a deadline date assignment on any task or milestone has the same results as assigning a “Finish No Later Than” or “Must Finish On”, without compromising the ability for schedule logic to drive the schedule.  Float is calculated against the deadline date as if it were a “FNLT” or “MFO” constraint, generating negative float when the task slips past it, but still allows for accurate critical path analysis against important events in time. 

Decision Authority -The individual authorized by the Agency to make important decisions on programs and projects under his/her authority. (PPC)

Decision Memorandum – The document that summarizes the decisions made at KDPs or as necessary in between KDPs.  The decision memorandum includes the Agency Baseline Commitment (if applicable), Management Agreement cost and schedule, UFE, and schedule margin managed above the Program or project, as well as life-cycle cost and schedule estimates, as required.

Defense Contract Management Agency (DCMA) – The Department of Defense (DoD) component that works directly with Defense suppliers to help ensure that DoD, Federal, and allied government supplies and services are delivered on time, at projected cost, and meet all performance requirements. As the DoD Executive Agent for EVMS, DCMA is responsible for ensuring the integrity and application effectiveness of contractor EVMS. The NASA Program/Project contracting officer will normally delegate the responsibility for verifying a supplier’s initial and continuing compliance with EIA-748 guidelines to the designated DCMA Administrating Contracting Officer (ACO) assigned to a DCMA Contract Management Office (CMO). (EVM)

Dependency Relationship – The relationship or logical sequence of the preceding activity to the succeeding activity.  An activity may have multiple preceding activities and multiple succeeding activities.  There are four dependency relationship models for the activities: 

  • Finish-to-Start (FS) – The successor activity cannot start until the predecessor activity has completed.  This is the most common linkage because it follows the most common work flow. 
  • Start-to-Start (SS) – The successor activity cannot start until the predecessor activity has started. This relationship is used when two activities need to begin at the same time.  This linkage is commonly used at major integration points or at the beginning of the project. 
  • Finish-to-Finish (FF) – The successor activity cannot finish until the predecessor activity has finished.  This relationship is used when an activity needs to finish and provide something to another activity so that it too can finish. 
  • Start-to-Finish (SF) – The successor activity cannot finish until the predecessor has started.  This relationship is very uncommon.

Detailed/Grassroots Estimating – A bottom-up technique for estimating schedule durations by estimating the lowest levels of the schedule or WBS and aggregating those numbers up to the summary nodes on the WBS.  Bottom up estimating is considered relatively accurate, but often tedious, technique for estimating.  This technique is the opposite of the top-down or analogous estimating approach.  See also Schedule Estimate and Bottom-Up Estimating.

Detailed Schedule – A representation of the IMS showing the lowest-level Program or project element schedules available that identify discrete work packages for a specific schedule element, such as a specific WBS.  Groupings of work packages may also be summarized to a higher detail (e.g., control accounts) in Detailed Schedules.   Detailed schedules illustrate horizontal dependencies and are used to track work progress at the lowest level.  Detailed schedules are logic network schedules (e.g., CPM), and should depict activity logic, start, finish, and baseline dates for detailed activities, as well as the total float for each detailed activity.  Detailed schedules should also reflect any other activity attributes, such as leads/lags, uncertainty/risks, etc.  It is critical that the activities in a detailed schedule be defined at a low enough level to allow for finish-to-start interdependency relationships where feasible, accurate progress measurement, issue identification, and traceability to higher level milestones.  In addition, detailed schedules should clearly identify the critical path(s).  If the detailed schedules are resource or cost loaded for the purposes of an ICSRA/JCL, they may also require traceability to the CBS.  See also Integrated Master Schedule (IMS) and Summary Schedule.

Development Costs– The total of all costs from the period beginning with the approval to proceed to Implementation at the beginning of Phase C through operational readiness at the end of Phase D. (PPC)

Direct Cost(s) – The expenditures for labor, material, and other direct cots (ODC) that reasonably can be related directly to performance of a unit of work, and which are charged directly and finally to the Program or project without distribution to an overhead or burden unit.

Discount Factor (also called the Discount Rate) – The factor that is used to translate values from different time periods so that they may be combined into a single number. Discount rates are utilized to calculate present value (PV). (CEH)

Discounted Cash Flow (DCF) – Refers to a cash flow summary that has been adjusted to reflect the time value of money. (CEH)

Discrete Effort – Tasks that are related to the completion of specific end products or services and can be directly planned and measured.

Discrete Risk – A known unknown that can be described by its cause, the possible event itself, and its consequences to the project or to an element such as the duration of activities (quantitative risk analysis) if it occurs.  Discrete risks generally have their existence probability of less than 100%.  As distinguished from a related concept – uncertainty – that has an implied probability of occurring of 100%.  See also Risk.

Distributed Budget – Budget that is assigned or allocated to Control Accounts, work packages, and planning packages. (SMH & EVM)

Driving Path – The critical path to an end item other than Program or project completion.  It is based on zero free float’s identifying the drivers to any activity, rather than the effect on total float.  See also Critical Path.

Double Counting – A situation that occurs in Monte Carlo simulations whereby the potential impact of uncertainties and/or risks are incorrectly accounted for more than once in an SRA/ICSRA.  Double counting usually occurs when: (1) uncertainties or risks are applied to activity durations or costs whose estimates were based on past Program or project data that already accounted for similar uncertainties/risks, (2) wide uncertainty distributions are applied to activity durations or costs that account for risk events that are also applied separately as discrete risk impacts, and (3) schedule duration uncertainty drives cost impacts that are also applied separately as cost uncertainties or risks.  It is important to avoid double counting when applying uncertainties and risks to an SRA/ICSRA.

Duration – The length of “working time” between the start and finish dates of an activity (i.e., number of working days), whether for a planning package or a work package.  Also referred to as Activity Duration, duration may be dependent upon the amount of resources applied/available, as well as the calendar applied to the activity.  Activity durations may have associated uncertainty and risks.  See also Program/Project Duration.

Return to Top

E

Early Finish Date – The earliest possible date an activity can finish without delaying the Program or project completion date; it is calculated by performing a forward pass.  See also Finish Date.

Early Start Date – The earliest possible date an activity can start without delaying the Program or project completion date; it is calculated by performing a forward pass.  See also Start Date.

Earned Schedule (ES) – The time that equates the budgeted cost of work performed (BCWP) to the budgeted cost of work scheduled (BCWS).  It provides the ratio of the Program or project time earned-to-date to the time the P/p should have earned.  It is analogous to the cost indicator for Cost Performance Index (CPI), as both are referenced to “actuals”.  ES describes schedule variance in time units and typically retains utility until P/p completion, as it does not automatically converge towards 1.0 near completion. 

Earned Value (EV) – The value of the work that has been performed (see also BCWP).

Earned Value Management – A project management approach for measuring and assessing project performance through the integration of technical scope with schedule and cost objectives during the execution of the project. EVM provides quantification of technical progress with objective performance measurement techniques, enabling management to gain insight into project status and project completion costs and schedules. Two essential characteristics of successful EVM are EVM system data integrity and carefully targeted monthly EVM data analyses (e.g., identification of risky WBS elements).

Earned Value Management Focal Point (EVM FP) – The EVM subject matter expert at each NASA Center/organization that serves as the point of contact for coordination and exchange of information on EVM. The EVM FP is responsible for effective policy implementation within their component, ensuring consistency with NASA policy and the provisions of this guide 

Earned Value Management Focal Point Working Group (EVMWG) – A group consisting of the EVM Subject Matter Experts from each Center and other organizations to facilitate Agency-wide communication, consistency, and lessons learned related to implementing and using EVM. 

Earned Value Management System (EVMS) – The integrated set of policies, processes, systems and practices that meet an organization’s implementation of EIA-748.  This integrated management system and its related subsystems allow for planning all work scope to completion; assignment of authority and responsibility at the work performance level; integration of the cost, schedule, and technical aspects of the work into a detailed baseline plan; objective measurement of progress (earned value) at the work performance level; accumulation and assignment of actual costs; analysis of variances from plans; summarization and reporting of performance data to higher levels of management for action; forecast of achievement of milestones and completion of events; forecast of final costs; and disciplined baseline maintenance and incorporation of baseline revisions in a timely manner.

Earned Value Management System Guidelines – The set of guidelines, established by EIA-748 that define the requirements the project/contractor must meet. 

Earned Value Management Working Group – A group consisting of the EVM Subject Matter Experts from each NASA Center and other subject matter experts to facilitate Agency-wide communication, consistency, and lessons learned related to implementing and using EVM. 

Earned Value Method – See Performance Measurement Technique (PMT). 

Earned Value Technique (EVT) – See Performance Measurement Technique (PMT). 

Effective Margin – The overall duration of margin that is calculated by zeroing out the margin tasks.  The most common approaches for calculating effective margin consist of zeroing out the margin activities and either 1) analyzing the float calculation on the constrained project finish or end item milestone, or 2) calculating how many days are between the unconstrained project finish or end item milestone and the project need date.  Note:  The cumulative margin may not equal the sum of the individual margin durations. 

Effort – The amount of work, or the number of work-time units used to complete an activity.  Effort is usually expressed in staff hours, staff days, or staff weeks.  Effort is not the same as Duration.

Electronic Industries Alliance (EIA) – The Institute that oversees the creation, promulgation and use of thousands of norms and guidelines that directly impact businesses in nearly every sector. This organization is also actively engaged in accrediting programs that assess conformance to standards—including globally-recognized cross-sector programs such as the ISO 9000 (quality) and ISO 14000 (environmental) management systems. The Earned Value Management System guidelines have been published as an EIA standard. 

Electronic Industries Alliance (EIA)-748, Earned Value Management Systems Standard – The set of guidelines that define the requirements an organization’s EVM system should meet. 

Element of Cost – Direct costs can be categorized to general types of resources that are represented within the direct cost value (e.g., labor, material, and ODC). (EVM)

Encumbrance – Encumbrance is the process by which a hold against UFE is made. The money has not necessarily been moved yet to the account that created the need, but the hold has been placed. It is different from a lien in that a lien identifies a specific task, a justification, and a cost and schedule impact whereas an encumbrance is just a monetary amount associated with that lien.(PPC)

Equipment – The reusable resource items such as test or manufacturing equipment and facilities.  See also Resource.

Established Standards Estimating – A top-down technique for estimating schedule durations based on well-established, historically validated and recorded durations for routine or procedurally-based activities or operations, such as hourly or daily rates per required quantity.  See also Schedule Estimate and Top-Down Estimating.

Estimate at Completion (EAC) – A value (expressed in dollars and/or hours) developed to represent a realistic projection of the final cost of a task (or group of tasks) when completed. EAC is the sum of direct and indirect costs to date, plus the estimate of costs for all authorized remaining work. EAC = Inception to date ACWP + ETC

Estimate to Compete (ETC) – A value (expressed in dollars and/or hours) developed to represent a realistic projection of the “to go” cost of the unaccomplished work to complete a task.

Expected (Planned) Finish Date – The finish date that the schedule logic network is calculating for a particular activity based on current Program or project status updates.  See also Finish Date.   

Expected (Planned) Start Date – The start date that the schedule logic network is calculating for a particular activity based on current Program or project status updates.  See also Start Date. 

Expert Experience and Judgment Estimating – A top-down technique for estimating schedule durations based on personal knowledge and/or experience with the same staff or from similar project work or specialized training, often guided by historic (actual) data.  See also Schedule Estimate and Top-Down Estimating.

External Replanning – A rescheduling action in which tasks for the remaining effort are replanned due to internal (to the Program or project) scope changes, new technical approaches, re-sequencing of activities, recovery or workarounds from technical problems, or to simply create more realistic schedules for the work remaining to be accomplished.  External replanning differs from internal replanning because it is driven by directed changes outside of the Program or project’s control such as a launch date change, budget cut, or other event.  See also Replan and Internal Replan

Extrapolation Estimating – A top-down technique for estimating schedule durations calculated from existing known relationships, data, and/or trends (e.g., 3-point time estimates).  See also Schedule Estimate and Top-Down Estimating.

Return to Top

F

Fast Tracking – A schedule acceleration technique that includes identification of activities on the critical path that can be partially overlapped or implemented completely in parallel instead of in sequence.  It is most often the discretionary dependencies that are discarded in order to fast track activities.  This technique may not always result in higher costs, but definitely could increase risk to the Program or project, especially in the area of delays due to rework.  See also Acceleration.

Field Code – Numerical or text values in the scheduling tool used to characterize schedule activity attributes (e.g., CAM, OBS, Milestone, CLIN, LOE, etc.) to facilitate filtering, ordering, sorting, or grouping of activities.

Finish Date – The date that an activity is predicted (or permitted) to finish, based on the analysis of the schedule.  There are four different representations of finish dates:  Early Finish Date, Late Finish Date, Expected/Planned Finish Date, and Actual Finish Date. 

Fixed Cost – The costs of an activity (manufacturing, production, assembly, operation, maintenance, etc.) that do not vary significantly with the measure of the product or service output. Though these costs will be incurred regardless of the output of the system, the starting point scope of fixed costs is often determined by factors that can be controlled, such as design, capacity planning, and infrastructure scope and business process steps. 

Float – The number of workdays that an activity can be delayed without impacting the start of a later activity.  Float is an automatic calculation performed by the scheduling tool; it is calculated by subtracting early dates from late dates (i.e., Float = Late Dates – Early Dates).  Float informs management as to which activities can be reassigned resources in order to mitigate slips in other activities.  Float should always have a positive value.  Negative float arises when an activity’s completion date, or associated milestone, is constrained—that is, when the constraint date is earlier than an activity’s calculated late finish.  In essence, the constraint states that an activity must finish before the date the activity is able to finish as calculated by network logic.  Date constraints causing negative float need to be justified or removed.  Zero float is an indication that an activity delay of a given number of days will result in a Program or project delay of the same number of days.  There are two types of float:  Free Float and Total Float.  Free Float has to do with the float on any activity, whereas Total Float is concerned with the Program or project finish or end-item date.  See also Free Float and Total Float.

Flow Diagrams – A communication tool that aids in the Program or project(P/p)’s understanding of activity relationships through use of diagrams that show major P/p integration points, as well as which subsystems and/or components flow into them.  Flow diagrams are typically developed prior to assigning activity dependency relationships.

Forecast – A prediction of when activities will start and/or such as when an activity that has already started is expected to finish, the amount of duration remaining in an activity already underway, when an activity that has not yet started is expected to begin, or an increase or decrease in duration, based on new information, of a future activity that has not yet started.  Forecasts may utilize estimating techniques, such as Extrapolation Estimating.

Forecast Accuracy/Realism – A schedule metric that helps to answer the question of whether the forecast is realistic.  It calculates the efficiency with which tasks have been accomplished when measured against the previous period forecasted completion dates.  It identifies whether the specific activities forecast for a period were actually accomplished.  Max value is 1.0.  Should be able to filter by activity and milestone. This metric uses forecast finish (or start) for events forecast in the previous month and compares the finish dates to see if they actually occurred.  This algorithm is much more complex since it needs to use data from a previous schedule (the UID and forecast finish/start dates) then uses the current period finish/start date to see if those events actually occurred during the current period.  Calculation:  Prior to “time now”:  # of tasks actually completed / number of tasks forecasted to finish in a previous version of the IMS; After “time now”:  # of tasks forecasted to complete / number of tasks forecasted to finish in a previous version of the IMS.

Formulation Authorization Document (FAD) – The document issued by the MDAA (or MSOD) to authorize the formulation of a program whose goals will fulfill part of the Agency’s Strategic Plan, Mission Directorate Strategies, or Mission Support Office Functional Leadership Plans. In addition, a FAD or equivalent is used to authorize the formulation of a project. 

Forward Pass – The calculation used by the scheduling software tool to determine the earliest possible start and finish dates for every activity in the schedule logic network.  The forward pass also determines the total time required for the entire Program or project by calculating the critical path.

Forecast Execution Index (FEI) – An IMS-based metric that calculates the efficiency with which tasks have been accomplished in a given month when measured against the forecasted task completions.  FEI can be over 1.0.  Calculation:  (prior to “time now”) FEI = # of tasks that were actually completed on or before IMS status date / # of tasks forecasted to complete in a previous version of the IMS; (after “time now”) FEI = # of forecasted to complete on or before IMS status date / # of tasks forecasted to complete in a previous version of the IMS.

FEI Example:

40 tasks forecasted to complete in Month X

42 tasks completed in Month X

30 tasks of the 42 complete were in the original 40 subset (thus 12 tasks were pulled in early, in addition to the original 10 that slipped out)

CEI/FA = 30/40 (75%) 

FEI = 42/40 (105%)

While you’re accomplishing more than originally planned (105%) for the month, your forecasting accuracy ability to hit specific tasks is lower (75%)

Free Float – Free Float refers to the amount of time a task can be delayed before impacting the early start date of its immediate successor(s).  See also Float (Slack).

Funded Margin – Identical in application to unfunded margin with the exception that appropriate funds for execution are set aside, within the Program or project (P/p) budget, to cover potential costs should the margin be needed.  The “funding” for funded schedule margin typically comes from Management Reserve (MR), which if available, is held by the P/p Manager.  Funded schedule margin is commonly used in most robotic missions.  See also Schedule Margin and Unfunded Schedule Margin.

Funding (budget authority) – The authority provided by law to incur financial obligations that will result in expenditures. There are four basic forms of budget authority, but only two are applicable to NASA: appropriations and spending authority from offsetting collections (reimbursables and working capital funds). Budget authority is provided or delegated to projects through the Agency’s funds distribution process.

Functional Breakdown Structure (FBS) – A structural alternative to a Work Breakdown Structure (WBS) that can be used for estimating cost. The FBS is organized by functions that must be performed to produce a product, rather than the end products themselves. The activities-based structure is not tied to any particular architecture because it is a listing of the needed functions, not the elements, of the architecture. 

Future Value (FV) – A financial term that establishes the value of an asset or set of cash flows at a future point, assuming certain interest rates. FV does not include corrections for inflation. FV is utilized in calculating the time value of money. 

Return to Top

G

Giver/Receiver – A representation of dependencies between schedules (e.g., hand-offs of products).

Grassroots Estimate – The estimate generated by computing the value of labor and materials for each Work Breakdown Structure (WBS) line item. It is also referred to as “bottom-up” or engineering buildup estimating. 

Ground Rules and Assumptions (GR&A) – A description of features that bound the cost estimates for a specified technical and programmatic scope. These allow the estimator to clearly communicate the content of the estimate to customers and stakeholders. 

Return to Top

H

Hammock Activity – An activity that spans between two points in a schedule and has no duration of its own.  It is linked to the start date of the first activity and to the finish date of the last activity in a sequence of activities.  The name comes from the anchoring of the activity to the first and last activities in the sequence of detailed activities in a specific section of the schedule being summarized, which is analogous to two trees that anchor a hammock.  Hammock activities are typically used to model soft or indirect costs (e.g., services and support costs) for LOE activities in an ICSRA (or JCL).  See also Level of Effort (LOE).

Hanging Logic – See Dangling Logic.

Hard Constraint – A type of constraint that fixes a schedule date and does not allow the logic to drive the schedule (i.e. either restricts all movement or restricts movement to the right) on the constrained task.  Hard constraints should be avoided except where absolutely necessary.  Types of hard constraints include:

  • Start No Later Than (SNLT) or Start On or Before.  An Activity or Milestone will start no later than the assigned start date.  However, it can start as early as necessary. 
  • Finish No Later Than (FNLT) or Finish On or Before.  An Activity or Milestone will finish no later than the assigned finish date.  However, it can finish as early as necessary.  This is a useful constraint to use for a contract deliverable milestone or project completion milestone.
  • Must Start On (MSO) or Start On or Mandatory Start.  An Activity or Milestone will start on the assigned date.  Use of this constraint overrides schedule date calculations driven by logic, resulting in a date that may be physically impossible to achieve.
  • Must Finish On (MFO) or Finish On or Mandatory Finish.  An Activity or Milestone will finish on the assigned date.  Use of this constraint overrides schedule date calculations driven by logic, resulting in a date that may be physically impossible to achieve.

Hit or Miss Index (HMI) – A special case of the Current Execution Index (CEI), that calculates the efficiency with which tasks have been accomplished when measured against the forecasted completion dates for the current month.  Calculation:  HMI = # of activities actually completed this month / # of activities planned to complete this month. 

Homoscedasticity – A statistical assumption that the variance of error is constant across the data (a necessary assumption in the use of Ordinary Least Squares (OLS) regression techniques).

Horizontal Traceability – A demonstration that the activities in the schedule are logically sequenced using proper relationship types that account for the interdependence of detailed activities, work packages, and planning packages.

Return to Top

I

Impact – See Consequence

Independent Estimate at Complete (IEAC) – The IEAC is a forecast of most likely total project costs based on assessment of historical project performance. 

Indirect Cost(s) – The cost for common or joint objectives that cannot be identified specifically with a particular Program or project or activity.  Indirect Costs consist of the cost of contracted services only and should include no civil service labor or travel costs.  Also referred to as overhead cost or burden. 

Inflation – The rise in the general level of prices of goods and services over time. Increases in inflation represent an erosion of the purchasing power of money. The inflation rate is an annualized percentage change in a price index over time.

Integrated Baseline Review (IBR) – A risk-based review conducted by Program or project Management to ensure a mutual understanding between the customer and supplier of the risks inherent in the supplier’s Performance Measurement Baseline (PMB) and to ensure that the PMB is realistic for accomplishing all the authorized work within the authorized schedule and budget. 

Integrated Cost and Schedule Risk Analysis (ICSRA) – The process of performing a probabilistic risk analysis on a Program or project schedule that is resource or cost loaded.  This type of probabilistic analysis utilizes Monte Carlo simulations that incorporate cost uncertainty distributions and schedule duration uncertainty distributions, as well as discrete risks that have a likelihood of impacting the costs and/or schedule.  See also Joint Confidence Level (JCL).

Integrated Cost and Schedule Risk Analysis Model (ICSRA Model) – The model used for estimating the probable future outcome of the Program or project’s integrated cost and schedule performance.  It utilizes the Analysis Schedule or complete IMS appended with costs (e.g., labor, travel, materials, equipment, and other direct and indirect costs), and affected by activity duration uncertainties, cost uncertainties, as well as identified discrete risks (or risk drivers) specified by their probability and impact on identified activities in the schedule.  See also Analysis Schedule, IMS, Uncertainty, Risk, and Schedule Risk Analysis Model (SRA Model).

Integrated Cost and Schedule Risk Analysis Report (ICSRA Report) – The documentation of results from an ICSRA.  See also Integrated Cost and Schedule Risk Analysis (SRA).

Integrated Master Plan (IMP) – A top level Program or project (P/p) plan hierarchy that is decomposed into P/p events, event accomplishments, and accomplishment criteria.  The IMP is typically not time phased and often serves as the basis for the P/p IMS.  (Note – IMPs are not typically used within NASA; however, contractors may use IMPs as a basis for their schedules.)

Integrated Master Schedule (IMS) – The complete, time-phased, logically-linked network of all P/p effort that is required to ensure that all objectives are met within approved commitments.  The use of the word “integrated” implies the incorporation of all activities, even contractor and subcontractor efforts, necessary to complete the P/p.  The IMS is utilized as the P/p management tool that integrates the planned work, the resources necessary to accomplish that work, and the associated budget.  The IMS is the backbone for managing the P/p successfully, which includes establishing the PMB utilized in EVM, measuring and forecasting performance, controlling the baseline, and communicating the overall progress against the plan. 

Integrated Program Management Report (IPMR) – Integrated Program Management Report. The standard report format to communicate program/project monthly cost/schedule performance and status between a contractor and the Government. The IPMR consists of seven report formats that provide program/project managers information to: integrate cost and schedule performance data with technical performance measures, identify the magnitude and impact of actual and potential problem areas causing significant cost and schedule variances, forecast schedule completions, and provide valid, timely program/project status information to higher management for effective decision making.  The formats consist of: Format 1- provides data to measure cost and schedule performance by product-oriented WBS elements, the hardware, software, and services the Government is buying; Format 2- provides the same data by the contractor’s organization (functional or Integrated Product Team (IPT) structure); Format 3- provides the budget baseline plan against which performance is measured;  Format 4- provides staffing forecasts for correlation with the budget plan and cost estimates; Format 5- is a narrative report used to explain significant cost and schedule variances and other identified contract problems and topics;  Format 6- Integrated Master Schedule (IMS); Format 7- time-phased historical and forecast cost submission. This is a contract data requirement when EVM is required.

Integrity – A property of the Program or project schedule that indicates it is complete, logically sound, and error free with respect to its mechanics and calculations.  Schedule Integrity is tested through the Schedule Health Check as part of Schedule Assessment.  See also Credibility, Validity, and Quality.

Interest – A fee charged for the use of money or capital paid by a borrower to a lender as a form of compensation for the use of the assets. 

Intermediate Schedule – A representation of the IMS at a lower resolution of work to be performed than what is depicted in the Summary Schedule, but at a higher level than the Detailed Schedule(s).  Early in the Program or project life cycle, intermediate schedules may represent early stages of the rolling wave approach (i.e., top-down).  Later in the life cycle, they may be summaries of more detailed schedules (i.e., bottom-up).  Intermediate schedules therefore reflect relationships among key events, start, finish, and baseline dates for summary activities, as well as total float for each summary task.  Intermediate schedules should also clearly identify the critical path.  Intermediate schedules should be organized according to the WBS and support the key dates in the Summary Schedule.  See also Integrated Master Schedule (IMS) and Detailed Schedule.

Internal Rate of Return (IRR) – A metric used in capital budgeting to measure and compare the profitability of alternate investments. It is also known as an effective interest rate or a discounted cash flow rate of return. The IRR is the annualized effective compounded rate of return that makes the net present value (NPV) of all cash flows from a particular investment equal to zero. 

Internal Replanning – A rescheduling action in which tasks for the remaining effort are replanned due to internal (to the Program or project) scope changes, new technical approaches, re-sequencing of activities, recovery or workarounds from technical problems, or to simply create more realistic schedules for the work remaining to be accomplished.  With an internal replan the external commitments remain unchanged (e.g. external control milestones, launch date, MA and/or the ABC date).  See also Replan and External Replan.

Return to Top

J

Joint Cost and Schedule Confidence Level (JCL) – The probability that cost will be equal to or less than the targeted cost and schedule will be equal to or less than the targeted schedule date.  The JCL calculation includes consideration of the risk associated with all elements, regardless of whether or not they are funded from appropriations or managed outside of the project. JCL calculations include the period from KDP C through the hand over to operations, i.e., end of the on-orbit checkout.

Return to Top

K

Key Decision Points (KDPs) – The event at which the Decision Authority determines the readiness of a Program or project to progress to the next phase of the life cycle (or to the next KDP). 

Key Milestones – An event of particular significance to Program or project Management that identifies significant, measurable progress.  Key Milestones may include Control Milestones or Notification Milestones.  See also Milestone.

Key Performance Parameters (KPPs) – The quantitative metrics selected by the PM in order to measure the effectiveness of the project in achieving their goals and the related mission success criteria.

Known Unknown – See Risk.

Return to Top

L

Lag (Positive Lag) – A period of time applied to a dependency relationship between two activities that delays the defined relationship execution.  Lags should not be used to represent work or to provide for hidden float in the schedule.  Since lags persist in the iterations of a Monte Carlo simulation, they may result in over-estimating schedule risk.

Late Finish Date – The latest possible date an activity can finish without delaying the Program or project completion date; it is calculated by performing a backward pass.  See also Finish Date

Late Start Date – The latest possible date an activity can start without delaying the Program or project completion date; it is calculated by performing a backward pass.  See also Start Date.

Lead (Negative Lag) – A period of time applied to a dependency relationship between two tasks that accelerates the defined relationship execution.  It represents an overlap in dependencies between two activities.  A lead value is the same as a negative lag value.  The use of leads should be avoided, as they are difficult to use correctly and imply that one can see correctly into the future to take some action

Learning Curve – The assumption that the more times tasks are performed, the less time will be required for each of the successive iterations, hence reducing the cost estimate. Learning curves can be calculated through several different equations. How a learning curve applies to the space sector is questionable where fewer items, rather than multiple items in a mass-production environment, are fabricated. 

Lease vs. Buy Decision – A specialized type of trade study that enables a decision to minimize Life Cycle Cost (LCC) outlays by comparing the cash flows associated with each alternative and assessing the best value. This specialized Business Case Analysis (BCA) is typically applied to information technology (IT) and facilities. 

Lesson Learned – The significant knowledge or understanding gained through past or current Program or projects that is documented and collected to benefit current and future Program or projects.

Level of Effort (LOE) – Work that does not result in a final deliverable (i.e., liaison, coordination, management, or other support activities), and which cannot be directly associated with a definable end product. It is measured “automatically by the passage of time” in terms of resources planned within a given fiscal period.  With LOE effort, BCWP is always equal to BCWS.

Liens (Risk) – Events that are having or likely to have a negative impact on project cost, schedule, or technical performance. May represent an encumbrance on project funds or UFE. 

Life Cycle Costs (LCC) – The total cost for all phases of a project or system, including design, development, verification, production, operations, maintenance, and disposal.  (Note:  NASA has included a detailed definition of project LCC in NPR 7120.5E.) 

Life Cycle Review (LCR) – A review of a Program or project (P/p) designed to provide a periodic assessment of the technical and programmatic (cost and schedule) status and health of a P/p at a key point in the life cycle, (e.g., Preliminary Design Review (PDR) or Critical Design Review (CDR)).  Certain LCRs provide the basis for the Decision Authority to approve or disapprove the transition of a P/p at a KDP to the next life-cycle phase.

Likelihood – Likelihood is one of two dimensions to risk; the other is the Consequence (i.e., impact) on the durations of activities the risk affects if it happens.  Also referred to as Probability.  See also Uncertainty and Risk

Longest Path – See also Driving Path and Critical Path.

Linear Regression – A statistical approach to modeling the relationship between a dependent variable and one or more explanatory variables. This is employed in the development and use of parametric cost estimating tools. 

Return to Top

M

Make vs. Buy Decision – An analysis that supports make-or-buy decisions, including both financial and strategic considerations, such as whether the element is critical to the success of the project, whether it fits into the desired future core competencies of the organization, or whether the item is so specialized that there are few or no other suppliers. 

Management Agreement (MA) – Within the Decision Memorandum, the parameters and authorities over which the PM has management control constitute the Program or project Management Agreement.  A PM has the authority to manage within the Management Agreement and is accountable for compliance with the terms of the agreement.  

Management Reserve (MR) – An amount of total Program or project budget withheld for management control and cost risk management purposes, rather than designated for accomplishment of a specific task or set of tasks.  MR is not part of the PMB. 

Margin – An allowance that is carried in budgets (now referred to as UFEs), as well as in schedule and technical performance parameters to provide for uncertainties and risks. Margins are typically established as a baseline in formulation and consumed as the project progresses through its life cycle. 

Master Schedule – A Summary Schedule is often referred to as a “Master Schedule” when it reflects a summary IMS for the complete Program or project, including all major deliverables as well as all individual WBS components.  Master Schedules are typically appropriate for reporting to senior management or other stakeholders. 

Memorandum of Understanding (MOU)– The MOU is a bilateral or multilateral document describing the agreements between two parties. 

Merge Bias – An indication of the complexity of the start of an activity due to having a large number of predecessor activities.  Activities with a large number of predecessors have a higher probability of being delayed because all links have to complete on time in order for the activity to start on time.   In other words, merge bias is the impact of having two or more parallel paths of activities, each with its own variability or uncertainty, merge into one milestone or other activity. 

Metadata Manager (MdM) – The MdM houses the WBS structure and supplies this information to the NASA Core Financial System [sometimes nicknamed SAP because the system is based on SAP (Systems, Applications, Products) business applications]) and other subsystems such as WebTADS, FedTraveler, and Contract Management. 

Milestone – An event of particular significance that identifies significant, measurable progress, but has no duration and consumes no resources.  It is a finitely defined event that constitutes the start or completion of an activity or occurrence of an objective criterion for accomplishment.  Milestones should be discretely identifiable; the passage of time alone is not sufficient to constitute a milestone.  However, milestones should be associated with schedule data to document when the milestone is to occur.  See also Key Milestones, Notification Milestones, and Control Milestones.

Milestone Registry – A table of Program or project control and notification milestones.  See also Key MilestonesControl Milestones and Notification Milestones.

Milestone Schedule – A summary level schedule that allows the Program or project to review and identify all of the significant and milestones that may exist in the course of a P/p.  Milestone schedules are helpful in making sure that nothing falls behind schedule of off the radar entirely.  NASA P/ps typically do not develop true milestone schedules, as they instead include key milestones within the Master Schedule, which is another type of Summary Schedule.  See also Integrated Master Schedule (IMS).

Mission Directorate Associate Administrator (MDAA) – Responsible for managing programs within the Mission Directorate; recommends the assignment of programs and Category 1 projects to Centers; assigns Category 2 and 3 projects to Centers; serves as the KDP Decision Authority for Category 2 and 3 projects; and has responsibility for all programmatic requirements.

Model – A representation of a system broken into its component factors, or parts, so as to mimic or behave as the actual system would, were such parts or factors to be varied and intermixed.  A model is used to gain knowledge about a system without actually executing the system. 

Modified Base Calendar(s) – Defines alternative working periods for selected Program or project activities.  See also Calendars.

Monte Carlo Simulation – A class of computational algorithms relying on repeated random sampling to compute results usually applied to a complex system that is not solvable by mathematical means.  This simulation method is most suited to uses where there is significant uncertainty in inputs.  For SRAs/ICSRAs, the Monte Carlo Simulation calculates numerous scenarios of a schedule model by repeatedly picking random values from the input variable distributions for each “uncertain” variable and calculating the results. Since any iteration may be the subject project, the only meaningful statement about results is a probabilistic one such as: “It is 70% likely that this project will finish on XX date or earlier.” 

Multivariate Regression – A mathematical modeling technique that relates two or more independent variables to a dependent variable through a predetermined equation that minimizes the sum of the squared error. 

Multicollinearity – A statistical phenomenon in which two or more predictor variables in a multiple regression model are highly correlated. In this state, the coefficient estimates may change erratically in response to small changes in the model or the data, thus potentially rendering calculations of individual predictors invalid. 

Return to Top

N

NASA Policy Directive (NPD) – Agency policy statements that describe what is required by NASA management to achieve NASA’s vision, mission, and external mandates and describe who is responsible for carrying out those statements.

NASA Procedural Requirements (NPR– Agency mandatory instructions and requirements to implement NASA policy as delineated in an associated NPD 

NASA Research Announcement (NRA) – A mechanism used to announce research opportunities in support of NASA’s programs. Respondents prepare proposals based on their ideas, unlike proposal responses to a specific Statement of Work (SOW) issued as a part of a Request for Proposal (RFP) process. NRA proposals may result in awards of grants, contracts, or cooperative agreements. 

NASA Structure Management (NSM) – The NSM is the internal coding schema used by the Agency to define and organize project work content. The WBS with its NSM nomenclature provides a common management framework for project management decisions and communication, the definition and authorization of work, the development of project schedules, and the planning and allocation of resources. This same coding system is also used to account for all financial activities associated with funds appropriated by Congress to accomplish project work.

Near-Critical Activity – An activity with total float that is within a narrow range of the critical path.  See also Critical Path Activity and Critical Activity.

Near-Critical Path – The second longest (secondary critical path), third longest (tertiary critical path), etc. sequence of tasks in the schedule from time now to the Program or project end date.  See also Critical Path.

Near-Driving Path – The second longest (secondary driving path), third longest (tertiary driving path), etc. sequence of tasks in the schedule from time now to an interim Program or project milestone.  See also Critical Path, Driving Path, and Stochastic Critical Path.

Negative Float – Negative float, also known as negative slack, is the amount of time beyond a Program or project’s scheduled completion that a task or tasks within the P/p requires.  See also Float (Slack).

Net Present Value (NPV) – The sum of the present values (a time-series of incoming and outgoing cash flows) minus the present value of the initial investment. 

New Obligation Authority (NOA) – The approval to obligate resources to the level specified.

Nominal Discount Rate – The term for a real discount rate that has been adjusted to reflect anticipated inflation rates. 

Nonlinear Regression – A statistical technique of modeling a nonlinear functional relationship in which observational data are modeled by a function that is a nonlinear combination of the model parameters and dependent on one or more independent variables. 

Normalize/Normalization – Analyzing the raw data and making adjustments for consistency.  The inconsistencies that may be found in a schedule dataset include changing definitions of schedule milestones (e.g., Program or project start date may be ATP or some other date), and the effects of production rates on the dataset being analyzed, if more than one unit is being produced, for example.  When analyzing a dataset, normalization considerations should include adjustments for the cost (currency, Base Year), size and weight, complexity or mission, frequency, and mission platform (crewed, robotic). Cost data are frequently normalized to remove the effects of inflation, for example.

Notification Milestones – Milestones controlled by the Program or project; however, the P/p must notify the sponsor or the stakeholders of any changes.  See also Milestone and Control Milestone.

Return to Top

O

Office of Chief Financial Officer (OCFO) – The OCFO provides leadership for the planning, analysis, justification, control, and reporting of all Agency fiscal resources.  The OCFO is responsible for EVM policy and guidance. 

Office of Management and Budget (OMB) – A Cabinet-level office which is the largest office within the Executive Office of the United States President. The OMB oversees and coordinates the Administration’s procurement, financial management, information, and regulatory policies. In each of these areas, the OMB’s role is to help improve administrative management, to develop better performance measures and coordinating mechanisms, and to reduce any unnecessary burdens on the public. 

Office of Procurement (OP– The Office of Procurement provides functional management, leadership, and policy direction of procurement and financial assistance activities (excluding Space Act Agreements) for the entire Agency. 

Open Ends – See Dangling Activity.

Ordinary Least Squares (OLS) – A statistical technique for estimating the unknown parameters in a linear regression model that minimizes the sum of squared distances between observed responses in a dataset and the responses predicted by the linear approximation. Where there is no multicollinearity and errors are homoscedastic and have a normal distribution, OLS is the maximum likelihood estimator.

Organizational Breakdown Structure (OBS) – The OBS is the “who” of Program or project(P/p) scope.  It is the hierarchical division of the organization structure that defines who performs the work.  Many P/ps require resources from more than one organization or department.  The use of a P/p OBS helps to identify the responsibilities, hierarchy, and interfaces between these organizations.  

Other Direct Cost (ODC) – These costs (or charges) represent resources not classified as labor or material. They include travel, services, computer charges, etc. 

Out-of-Sequence Logic – Inconsistencies between logic and progress/status updates.  This occurs when a successor activity is in progress or complete before its predecessor activity starts.

Output – For the purpose of the Schedule Management Handbook, an “output” is any item generated by one of the PP&C functions. Outputs can be an input to another function or may be delivered/provided external to the project. 

Over Target Baseline (OTB) – A budgeted amount above the Project Budget Base/ CBB. The OTB term is used to describe the condition when the total allocated budget (TAB) exceeds the PBB/CBB. It is the end result of a formal reprogramming process. 

Over Target Schedule (OTS) – An established schedule that extends beyond the contractual milestones or delivery dates. 

Return to Top

P

Payback Period – The time required for the cumulative value of savings to equal the cumulative value of the investment. Achievement of payback is sometimes referred to as the “break-even point.”

Parametric Schedule Estimating – A top-down technique for estimating schedule durations, which derives time estimates from an arithmetical relationship among variables (i.e., Schedule Estimating Relationships (SERs), discussed in SMH Section 6.3.2.1.3.1), such as weight, power, mass, cost, etc.  See also Schedule Estimate and Top-Down Estimating.

Parametric Cost Estimate – An estimate generated by methods utilizing statistical relationships between historical costs and other project variables such as a system’s physical or performance characteristics.

Passback – In the spring of each year, OMB issues planning guidance to executive agencies for the budget beginning October 1 of the following year. In September, agencies submit their initial budget requests to OMB. During October and November, OMB staff review the agency budget requests against the President’s priorities, program performance, and budget constraints. In November and December, the President makes decisions on agency requests based on recommendations from the OMB director. OMB informs agencies of the President’s decisions in what is commonly referred to as the OMB “passback.” Agencies may appeal these decisions to the OMB director and in some cases directly to the President, but the timeframe for appeals is small. 

Percent Complete – A measure of how “done” an activity actually is that best represents what has been accomplished. 

Performance Measure – A metric to measure the extent to which a system, process, or activity fulfills its intended objectives.

Performance Measurement Baseline (PMB) – The time-phased budget plan for accomplishing all authorized work scope in a project’s life cycle, which includes both NASA internal costs and supplier costs. The PMB is used to measure project performance using earned value management, if required, or other performance measurement techniques if EVM is not required. It is formed by the budgets assigned to scheduled control accounts and the applicable indirect budgets. For future effort, not planned to the control account level, the PMB also includes budgets assigned to higher level WBS elements and undistributed budgets. The PMB does not include UFE, or management reserve (MR) for contractors.

Performance Measurement Technique (PMT) – The method or “algorithm” used to calculate earned value at the work package level. 

Performing Organization – A defined organizational unit in the OBS which applies the resources to accomplish the work.

Planned Value (PV) – See Budgeted Cost for Work Scheduled (BCWS).

Planner/Scheduler (P/S) – The role of the Planner/Scheduler (P/S) is to implement SMP processes in order to ensure the Program or project(P/p)’s objectives are successfully achieved.  The P/S must be familiar with the P/p technical scope and be able to translate that information into the network logic model that becomes the baseline IMS.  The P/S accomplishes this, in part, by:  1) facilitating planning through coordination with the project team to define project requirements and schedule objectives; 2) developing the IMS; 3) assessing all schedule products to ensure integrity; 4) performing schedule control by assisting the project team in managing changes to the IMS, which includes baseline change control; and 5) providing insight to the project team by reporting schedule progress, performance, variances, and forecasts.  The P/S is also responsible for utilizing P/p management software tools and techniques to develop, assess, maintain, and control the IMS.  Finally, P/p P/Ss must be able to communicate and coordinate effectively with all members of the project team, be proactive in their approach to problem solving, understand P/p management processes, and be able to report findings to P/p management.  While the terms Planner and Scheduler are often interchangeable insofar as both Planners and Schedulers perform Schedule Development (i.e., scheduling), one primary distinction is that a Planner may also oversee schedulers who perform many of the status collection, data input and report generation duties.  The Planner is typically in a more senior-level career position, having knowledge and experience related to the integration of multiple programmatic disciplines (e.g., cost, schedule, risk), and is more involved in determining Schedule Management approaches, performing detailed schedule analysis and workaround planning to aid in decision-making, and facilitating management-level discussions related to the P/p schedule. 

Planning Package (PP) – A segmented portion of discrete Program or project scope spanning multiple Control Accounts, normally the far-term effort, that can be identified and budgeted in early baseline planning but is not yet defined into work packages.  PPs are logically linked in the IMS, but performance cannot be taken against the PP for EVM purposes.  See also Work Package (WP).

Predecessor – An activity or milestone that must occur either partially or entirely prior to another task.  

Present Value (PV) – The value on a given date (present) of a payment or series of payments made at other times. Future cash flows are discounted to reflect the time value of money or investment risk. PV calculations are used to provide a means of comparing cash flows of various alternatives.

Price Variance (PV) – For material analysis, PV = (Budgeted Price – Actual Price) x (Actual Quantity). Quantity breakouts are most useful on programs procuring multiple items of the same part number, typical for production type contracts. 

Primary Critical Path – See Critical Path.

Probability – The extent to which an event is likely to occur.  As it pertains to risk, probability is a measure of the likelihood or frequency a risk event or condition will occur.  Probability is one of three dimensions to risk that also include the impact if the risk occurs and the activities or cost elements that would be affected if the risk occurs.  Generally, this probability determines the percentage of iterations in a simulation that includes the risk’s impact on activities assigned.  See also Likelihood, Risk, and Uncertainty. 

Probabilistic Branching – An analysis technique through which an activity (or series of activities in a path) in the schedule is randomly selected to occur given some probability.  Probabilistic branching is used to model a random selection between two or more alternative paths of activities that occur at random.  Probabilistic branching may be used for Analysis of Alternatives or in Schedule Risk Analysis.  See also Conditional Branching.

Probabilistic Critical Path – See Stochastic Critical Path.

Probability Density Function (PDF) – A function that describes the relative likelihood for a random variable to have a given value. The probability for the random variable to fall within a particular region is given by the integral of the variable’s density over the region. It is not negative, and its integral over the entire space is equal to one.

Probabilistic Cost or Schedule Estimate – An estimate that incorporates risks, uncertainties, and Monte Carlo simulations to provide a cumulative distribution function (S-curve) of the probability of a variable with a given probability distribution being less than or equal to a value. See also Probabilistic Estimating and Schedule Estimate

Probabilistic Estimating – A schedule estimating technique that incorporates the probability and impact of uncertainties and risks through a Monte Carlo simulation (or other probabilistic means) to provide a cumulative distribution function (S-curve) of the confidence levels (i.e., probability) associated with the possible range of schedule completion (or other selected milestone) dates.  Probabilistic Schedule Estimating can be top-down or bottom-up depending on the level of detail being utilized in the estimate, but typical Monte Carlo simulation exercises build up the risk component from the bottom, starting with a deterministic schedule and adding uncertainty and then identifiable risks.  Probabilistic Schedule Estimating also identifies the stochastic, or risk-informed, critical path(s).  See also Probabilistic Schedule EstimateSchedule Estimate, Top-Down Estimating, Bottom-Up Estimating, Critical PathStochastic Critical Path, and Driving Path(s).

Procurement – The acquiring of supplies or services (including construction) by contract with appropriated funds by and for the use of the Federal Government through purchase or lease whether the supplies or services are already in existence or must be created, developed, demonstrated, and evaluated. 

Procurement Strategy Meeting (PSM) – A forum where management reviews and approves the approach for the Agency’s major and other selected procurements. Chaired by the Assistant Administrator for Procurement (or designee), the PSM addresses and documents information, activities, and decisions required by the FAR and NFS and incorporates NASA strategic guidance and decisions from the ASM to ensure the alignment of the individual procurement action with NASA’s portfolio and mission. 

Program – A strategic investment by a Mission Directorate or Mission Support Office that has a defined architecture and/or technical approach, requirements, funding level, and a management structure that initiates and directs one or more projects. A program defines a strategic direction that the Agency has identified as critical. 

Program Baseline – The Program Baseline is associated with a major Program and represents the Program’s authorized value (with an associated scope and schedule) to include and some Unallocated Future Expenditures (UFEs), Management Reserve, Distributed Budget, Undistributed Budget (UB), and Authorized Unpriced Work (AUW).  At the Program level the Program Baseline is principally a funding baseline.

Program Plan – The document that establishes the program’s baseline for implementation and is signed by the MDAA, Center Director(s), and program manager.

Program Planning Budget Execution (PPBE) – A financial document that indicates planned expenditures or a funding request for future years for a project.

Progressive Elaboration – A technique used in Rolling Wave Planning that involves continuously improving and detailing a plan as more detailed and specific information and more accurate estimates become available.  See also Rolling Wave Planning.

Project – A specific investment identified in a Program Plan having defined requirements, a LCC, a beginning, and an end. A project also has a management structure and may have interfaces to other projects, agencies, and international partners. A project yields new or revised products that directly address NASA’s strategic goals. 

Project Budget Base (PBB) – The negotiated value of the project plus the estimated cost of authorized unpriced work. It is the Government project equivalent to the Contract Budget Base. It includes the PMB and MR. Customer approval is generally required to change it. 

Project Control Account Manager (P CAM) – A NASA manager responsible for task performance of a Control Account within the PMB and for planning and managing the resources authorized to accomplish such task. 

Project Duration – The length of “working time” between the start and finish dates of the Program or project(P/p) (i.e., number of working days), whether for a planning package or a work package.  P/p duration may be dependent upon the amount of resources applied/available, as well as the calendars applied to the schedule activities.  See also Duration.

Project Plan – A detailed plan which, when formally approved, sets forth the agreement between a program manager and Project Managers, and defines the guidelines and constraints under which the project will be executed. 

Return to Top

Q

Quality – A property of the Program or project schedule that indicates it is structurally sound.  Schedule Quality is tested as part of Schedule Assessment.  See also Credibility, Integrity, and Validity, and Quality.

Qualitative Data – Data that is categorical or subjective in form.  In risk analysis this refers to a probability of the risk’s occurring and the impact on the total project objective (finish, total cost). A structured model such as a schedule or cost estimate is not used in this method.

Qualitative Analysis – A non-numerical and subjective method for assessing the possibility for meeting the project cost or schedule objectives.  It often includes comparing characteristics or elements to gain insight, which Program or project management can use in the decision-making process. 

Quantitative Data – Data that is numerical in form, such as specific probability and impact multipliers.  For scheduling, it includes the deterministic estimate of activities’ durations.

Quantitative Analysis – A mathematical and statistical method of studying behavior and predicting outcomes, which Program or project management can use in the decision-making process.  For schedule risk analysis, this usually takes the form of a Monte Carlo simulation of a schedule with uncertainty and risks calibrated and assigned to activities.

Quantitative Risk Analysis (QRA) – A risk-intensive method for probabilistically summarizing risks for use in UFE sizing, resource management, cost estimating, and other PP&C-related activities. 

Return to Top

R

Real Discount Rate – The adjustment of a discount rate to eliminate the effects of expected inflation. It is used to discount CY dollars, real benefits, or costs.

Rebaselining – The process that results in a change to a Program or project’s Management Agreement (MA) or Agency Baseline Commitment (ABC).  This agreement establishes and documents an integrated set of project requirements, cost, schedule, technical content, and an agreed-to Joint Confidence Level (JCL) that forms the basis for NASA’s commitment with the external entities of OMB and Congress. 

Reciprocity. – A reciprocal arrangement or relationship which allows two or more groups to agree to the acceptance of another organizations’ EVMS, thereby reducing the burden of multiple reviews by individual groups. 

Regression Analysis – An analysis that explains how the value of a dependent variable changes when any one of the independent variables is changed while the other independent variables are held constant. Linear regression and Ordinary Least Squares (OLS) regression are parametric in that the regression function is defined in terms of a finite number of parameters that are estimated from the data. 

Relationship – See Dependency Relationship.

Remaining Duration – The expected or required time to complete an activity, calculated as the difference between the current date and the expected/planned finish date for in-progress activities.

Replanning – The process by which a program or project updates or modifies its plans. This applies to a change in the original authorized PBB or CBB planning for accomplishing formally authorized requirements, typically involving the redistribution of budget for remaining work. In accordance with the EIA-748, traceability is required to previous baselines, and funding requirements need to be considered in any replanning effort. There are two types of replanning:

  • Internal Replanning. Replanning actions performed by the supplier for remaining effort within the recognized PBB or CBB. It is caused by a supplier’s need to accommodate cost, schedule, or technical problems that may have made the original plan unrealistic. Internal replanning is restricted to remaining effort and if significant, the customer must be advised of the action.
  • Authorized Change (or External) Replanning. A change necessitated by government/ customer direction which may be in the form of either a definitized or a no cost contract change order for contracts or formal change to the Project Plan for in-house Projects that calls for a change in the original plan. It most often results from a change in the authorized requirement affecting cost, schedule, technical parameter or a combination thereof. 

Reprogramming (or Formal Reprogramming) – A comprehensive replanning of the remaining PMB that results in an Over-Target Baseline (OTB), an Over-Target Schedule (OTS) or both. This type of replan is for performance measurement purposes only and requires prior coordination and approval of the Customer. 

Request for Proposal (RFP) – A contractual document that provides a formal invitation to submit a proposal for a scope of work with the intent of forming a contract.

Reserves – “Reserves” is not a term used for any form of schedule margin, but may refer to forms of funding (e.g., Management Reserve).

Residual Risk – The remaining risk that exists after all mitigation actions have been implemented or exhausted in accordance with the risk management process.

Resource – The source required to perform work.  For Program or project s, resources can generally be put into three categories:  See also Workforce, Equipment, and Consumables.

Resource Calendar – Defines the working period/availability for a specific resource.

Resource Dictionary – See Resource Pool.

Resource-Driven Activity – An activity for which duration is dependent upon the amount of resources assigned or available.

Resource Leveling – The process for the sequencing of schedule activities, without violating network logic, for a given resource or resources in a manner that accounts for the resource’s availability and results in a more consistent level of demand for that resource or resources over the life cycle of the Program or project.  Resource leveling can be performed manually or it can be automated by the scheduling tool.

Resource Library – See Resource Pool.

Resource-Loaded Schedule – A schedule whereby specific resources have been mapped to specific activities.  See also Resource Loading.

Resource Loading – The process of assigning specific resources (i.e., workforce, materials, equipment, etc.) to a schedule activity or a group of activities for the purposes of estimating Program or project duration, cost, feasibility, and workforce planning.  See also Resource-Loaded Schedule.

Resource Pool – A single file containing all resource information for the schedule.  Also referred to as a Resource Library or Resource Dictionary.

Resource Rate – The cost per unit of time for a specific resource.

Resource Updates – Adjustments to resource requirements or allocation when using resource-loaded schedules.

Responsibility Assignment Matrix (RAM– A chart showing the relationship between the WBS elements and the organizations assigned responsibility for ensuring their accomplishment. The RAM normally depicts the assignment of each control account to a single manager, along with the assigned budget. The RAM is the result of cross-referencing the OBS with the WBS. Cross-referencing the WBS and OBS creates control accounts that facilitate schedule and cost performance measurement. The control account is the primary point for work authorization, work performance management, and work performance measurement; i.e., where the planned value is established, earned value is assessed, and actual costs are collected.

Responsible Organization – A defined organizational unit in the OBS which is assigned the responsibility to accomplish specific activities.

Return on Investment (ROI) – The ratio of money gained or lost on an investment relative to the money invested, which is normally expressed as a percentage. The ratio is sometimes referred to as a Rate of Return (ROR). 

Risk – (1) The combination of the likelihood (i.e., probability of occurrence) and the consequence(s) (i.e., impact) of a future undesired event or scenario occurring. Uncertainties are included in evaluation of likelihood and consequence of risk scenarios.  (2) The potential for shortfalls with respect to achieving explicitly established and stated objectives.  As applied to Program or project s, these objectives are translated into performance requirements, which may be related to institutional support for mission execution or related to any one or more of the following domains:  Safety, Mission Success (Technical), Cost, and Schedule.  Risk is operationally characterized as a set of triplets:  ScenarioLikelihood, and Consequence.  Discrete risks generally have their existence probability of less than 100%, as distinguished from a related concept – uncertainty – that has an implied probability of occurring of 100%.  Also referred to as Discrete Risk or Known Unknown.  See also Uncertainty. Note: NPR8000.4

Risk Assessment – An evaluation of a risk item that determines: (1) what can go wrong, (2) how likely is it to occur, (3) what the consequences are, (4) what the uncertainties are that are associated with the likelihood and consequences, and (5) what the mitigation plans are. 

Risk Drivers Method – A schedule risk analysis technique that models schedule and cost risk based upon the use of project-specific risks where the impact is specified as a distribution of multiplicative factor that, chosen randomly through the simulation, multiply the scheduled duration of activities affected.  Risks can be assigned to multiple activities and some activities may be influenced by multiple risks.  The Risk Drivers Method models how correlations occur due to risks influencing multiple activities or cost items, thus relieving the analyst from estimating correlation coefficients between activities.

Risk-Informed Critical Path – See Stochastic Critical Path.

Risk-Informed Decision Making (RIDM). A risk-informed decision-making process that uses a diverse set of performance measures (some of which are model-based risk metrics) along with other considerations within a deliberative process to inform decision making. 

Risk-Informed Schedule – See Probabilistic Schedule Estimate.

Risk List (Register) – The document or database containing all identified risks relevant to the Program or project. Usually developed in qualitative terms in risk workshops and interviews.  Includes the cause-risk-consequence form of the risk statement, as well as the probability and impact on project objectives, such as finish date and total cost.  Often contains statements about risk responses and distinguishes pre-response from post-response (residual risk) parameters.

Risk Management – Risk management includes RIDM and CRM in an integrated framework. RIDM informs SE decisions through better use of risk and uncertainty information in selecting alternatives and establishing baseline requirements. CRM manages risks over the course of the development and the Implementation Phase of the life cycle to ensure that safety, technical, cost, and schedule requirements are met. This is done to foster proactive risk management, to better inform decision making through better use of risk information, and then to more effectively manage implementation risks by focusing the CRM process on the baseline performance requirements emerging from the RIDM process. (See NPR 8000.4, Agency Risk Management Procedural Requirements.) These processes are applied at a level of rigor commensurate with the complexity, cost, and criticality of the project. 

Risk Management Plan (RMP) – The document that describes how risks will be identified and managed for a specific program/project. 

Risk Mitigation – Taking steps to reduce the adverse effects of risk.  With respect to Schedule Management, this may mean adding risk mitigation activities to the schedule to lessen potential risk impact(s).  Mitigation activities need to be: (1) different from what has been in place before, (2) committed to by the participants (e.g., owner and contractor, other stakeholders) and (3) monitored for effectiveness and adjustment if needed.  Mitigation is one approach to a Program or project taking longer than desired.

Risk Posture – The summed view of a Program or project’s exposure to uncertainties and risks.  Risk posture helps to define the probability or “P value” of success that determines the total contingency of time and/or cost.

Rolling Wave Planning – A planning technique that uses progressive elaboration and allows scheduling to occur in waves with only imminent activities planned in detail (work package), while activities further in the future are planned at a higher level (planning package).

Rough Order of Magnitude (ROM) – An estimate based on an approximation without benefit of details or detailed analysis. 

Return to Top

S

S-Curve – The curve that represents a Sigmoid function produced by a probabilistic risk analysis, such as an SRA/ICSRA.  See also Cumulative Distribution Function 

Scenario – An event or sequence of events, such as an account or synopsis of a projected course of action or events.  See also Risk.

Schedule – The Program or project management tool that communicates what work needs to be performed, the logical sequences in which the work is planned to be performed, which resources of the organization will perform the work, and the timeframes in which that work needs to be performed.  A schedule typically includes a logically-linked network of Program or project milestones, activities, and deliverables, with intended start and finish dates, and durations.

Schedule Activity Duration Estimate – An estimate of schedule activity durations.  Several techniques available for estimating schedule activity durations include:  Analogous EstimatingExpert Experience/Judgment Estimating, Established Standards Estimating, Extrapolation Estimating, Parametric Estimating, Bottom-Up/Grassroots Estimating, and Brainstorm Estimating.  See also Schedule Estimate.

Schedule Analysis – A sub-function of Schedule Management that facilitates evaluating the magnitude, impact, and significance of actual and forecast variances to the schedule and/or baseline due to schedule uncertainty and risk.  For purposes of this handbook, Schedule Analysis is synonymous with Schedule Risk Analysis.  See also Schedule Management, and Schedule Assessment and Analysis.   

Schedule Analyst – The role of the Schedule Analyst is to perform analysis that will aid in identifying deviations from NASA’s Schedule Management best practices and risks that may compromise the project’s plan.  The Schedule Analyst is responsible for verifying the integrity of the schedule, analyzing the critical path(s) to determine that all critical activities are being properly tracked, and conducting schedule risk analysis to understand how risks and uncertainty may alter the likelihood of potential driving paths to specific milestones and negatively impact the availability of margin.  The Schedule Analyst is also responsible for analyzing the cost, schedule, and risk elements collectively for a holistic view of the project’s programmatic health.  The Schedule Analyst is responsible for building integrated models (SRAs and/or JCLs) and performing sensitivity analyses that can provide management with insight into different scenarios for prioritizing resources and margin to address top Program or project (P/p) risks and threats.  The Schedule Analyst must be able to communicate assessment findings with P/p management as well as senior management.   As it pertains to independent assessment, the Schedule Analyst is the focal point for assessing the IMS health and schedule BOEs, providing expert opinion of the schedule performance, conducting Schedule Risk Analysis (SRA), Joint Confidence Level (JCL) analysis, and identifying schedule findings to the Standing Review Board (SRB).  The Schedule Analyst works closely with the Cost Analyst throughout the entire SRB evaluation period to ensure that schedule and cost analysis results are consistent and complementary.

Schedule Assessment – A sub-function of Schedule Management that facilitates determining the validity and integrity of the schedule.  Schedule Assessment tests include:  Compliance Test, Analogy Test, Schedule BOE Quality Test, Schedule Health Check, Critical Path Test, Structural Test, and Resource Integration Assessment.  See also Schedule Management, and Schedule Assessment and Analysis.  

Schedule Assessment and Analysis – Two complementary sub-functions of Schedule Management that are initiated early in formulation and utilized routinely to determine the validity and integrity of the schedule, and evaluating the magnitude, impact, and significance of Program or project (P/p) uncertainties and risks associated with meeting P/p and Agency commitments.  See also Schedule ManagementSchedule Assessment, and Schedule Analysis

Schedule Assessment and Analysis Report – A report, typically delivered monthly, which captures schedule assessment and analysis findings used for schedule maintenance and control.  See also Schedule Report and Forecast Reporting.

Schedule Basis of Estimate – A document(s) that details the premise, or basis, from which critical aspects of activity duration estimate were developed including ground rules, assumptions, WBS Dictionary description, schedule development methodology, resource assumptions and estimates, duration uncertainty, risk, cost and/or labor estimates, any studies or analysis used as a reference, and any other details which influenced the schedule duration estimates.  See also Basis of Estimate (BOE).

Schedule Change Management – The process for managing changes to the schedule.  The schedule change management process is necessary when verifying/modifying activity and milestone durations, revising or adding logic interdependencies, adding new activities and/or milestones and their associated logic ties, re-allocating/assigning resources, changing calendars, or other miscellaneous, minor schedule adjustments.  See also Change Control Board (CCB).

Schedule Control – A sub-function of Schedule Management that facilitates performance measurement and corrective actions needed to ensure the timely execution of the activities.  It is imperative for Schedule Control to be performed in conjunction with Schedule Assessment and Analysis to ensure the integrity of the entire Schedule Management function.  See also Schedule Management and Schedule Maintenance and Control.

Schedule Development – A sub-function of Schedule Management initiated early in formulation of a Program or project with the objective to define, develop, and deploy a scheduling capability, including the capability to display time-phased activities in an IMS and to export specific outputs as required for the other Schedule Management sub-functions.  See also Schedule Management.

Schedule Documentation and Communication – Two complementary sub-functions of Schedule Management that facilitate the recording and dissemination of schedule information and required products at varying levels of maturity, using established configuration and data management (CM/DM) processes, as well as communication aids and tools throughout the Program or project life cycle.  See also Schedule Management.

Schedule Estimate – An estimate of the overall Program or project schedule.  Several techniques available for estimating schedule activity durations include:  Analogous EstimatingExpert Experience/Judgment Estimating, Established Standards Estimating, Extrapolation Estimating, Parametric Estimating, Bottom-Up/Grassroots Estimating, and Brainstorm Estimating.  See also Schedule Estimate.

Schedule Estimating Relationship (SER) – A relationship used in parametric estimating that defines schedule as a function of one or more parameters or factors, which may include technical parameters, as well as parameters for cost.  SERs are analogous to cost estimating relationships (CERs).  See also Parametric Estimating.  

Schedule Execution Metrics – Metrics intended to assist the Program or project management in using the schedule to make sound programmatic and schedule control decisions.

Schedule Forecast Reporting – This category of communication and reporting refers to any report generated from a stochastic or probabilistic modeling technique such as a SRA/ICSRA.  This schedule report also involves comparison, trend or generates a metric that is risk and uncertainty informed including predictions utilizing EVM metrics.   Examples of forecast reports include:  Probability of On-time Delivery of Critical Items Reports, Confidence Level Reports, and JCL Reports.  See also Schedule Reports and Schedule Assessment and Analysis Reports.

Schedule Logic Network  A schedule model that reflects the planned Program or project implementation and sequencing through the use of activities/milestones, dependencies, durations, and date constraints.  It expresses the logic as to how the work scope will be accomplished.  Logic Network schedules are the basis for critical path analysis, which is a method for identification and assessment of schedule priorities and impacts.  See also Integrated Master Schedule (IMS).

Scheduling – Scheduling is a process used to develop, document and maintain the Program or project schedule.  See also Schedule, Schedule Development, and Schedule Maintenance.

Schedule Maintenance – A sub-function of Schedule Management that facilitates routine updates the schedule database with data from current performance reports as well as implementing approved change orders.  See also Schedule Management and Schedule Maintenance and Control.

Schedule Maintenance and Control – Two complementary sub-functions of Schedule Management that facilitate the routine updating of progress, the tracking and monitoring of schedule performance, and the execution of corrective actions as determined from the performance measures.  See also Schedule Management, Schedule Maintenance, and Schedule Control.

Schedule Management – The programmatic function that provides the framework for coordinating, communicating, time phasing, and resource planning the necessary tasks within a work effort in order to manage and optimize the available resources and deliver products on time and within budget.  Schedule Management is composed of the following sub-functions:  Planning, Development, Assessment and Analysis, Maintenance and Control, and Documentation and Communication.

Schedule Management Plan – The definitive instruction that guides the development, implementation, and execution of all Schedule Management sub-functions.

Schedule Management Planning – A sub-function of Schedule Management that facilitates the design, development and implementation of all Schedule Management processes, tools, reporting forms, and formats.  See also Schedule Management.

Schedule Margin – The allowance carried in projected schedules to account for uncertainties and risks. Margins are allocated during the schedule formulation process based on assessments of risks and are typically consumed as the program/project proceeds through the life cycle.  

Schedule Model – Consists of the entire database of all schedule data including all the activity attributes, and all directly related supporting documentation such as Bases of Estimates (BoEs), Flow Diagrams, Agency-directed Guidance, etc.  See also Schedule Report.

Schedule Narrative – A document(s) that contains Program or project schedule information in a meaningful format with content defined and documented.  Schedule Narrative should be collected along with routine schedule progress/status updates (e.g., schedule change logs).  Schedule Narrative is also an important component of schedule archiving and should present a story of the P/p that highlights the major events and the effect of any changes.

Schedule Performance Index (SPI) – An indicator of the schedule efficiency at which work has been performed to date.  Calculation:  SPI = BCWP / BCWS or EV/PV (i.e., Earned Value divided by Planned (Budgeted) Value).  An index of 1.0 means the work is being performed right to the schedule. SPI > 1.0 means that the work is ahead of schedule. SPI < 1.0 means that the work is behind schedule. 

Schedule Performance Measures – Measurements produced by incorporating current performance data with the planned performance in the Program or project schedule.  See also Schedule Performance Report.

Schedule Performance Report – A management report, typically delivered monthly, which captures schedule performance measures used for schedule maintenance and control.  See also Schedule Performance Measures and Schedule Report.

Schedule Progress Reporting – Progress reporting refers to any report generated from schedule data involving a comparison (e.g., variance) or trend.  Although these reports often project future activity/milestone dates, the comparisons, calculations, and/or metrics are deterministic in nature, not accounting for the uncertainty and risk inherent in forecasting.  Examples of Schedule Status and Progress Reports include:  Milestone Variance Reports/Logs, Milestone Trend Reports, Summary Schedule Variance Reports, IMS Reports, Float/Slack Trend Reports, Margin Trend Reports/Logs, EVM Reports, Risk-Based Completion Trend Reports, and Schedule Risk Analysis Reports.  See also Schedule Report and Schedule Performance Report.

Scheduler – See Planner/Scheduler.

Schedule Report – An output of the Schedule Model that is used for various management activities, such as analysis or control, and is repeated at pre-determined intervals, usually monthly.  See also Schedule Model, Schedule Performance Measures, Schedule Performance Report, and Schedule Assessment and Analysis Report.

Schedule Risk Analysis (SRA) – The process of performing a probabilistic risk analysis on a Program or project (P/p) schedule.  SRA is based on using Monte Carlo simulations that incorporate duration uncertainty distributions, as well as discrete risks that have a likelihood of impacting the schedule.  The SRA produces a confidence level for meeting the P/p completion (or other key milestone) date.  See also Confidence LevelIntegrated Cost and Schedule Risk Analysis (ICSRA), and JCL.

Schedule Risk Analysis Model (SRA Model) – The model used for estimating the probable future outcome of the Program or project’s schedule performance.  It utilizes the Analysis Schedule or complete IMS that is loaded with activity duration uncertainties and discrete risks.  See also Analysis Schedule, IMS, Uncertainty, Risk, and ICSRA Model.

Schedule Risk Analysis Report (SRA Report) – The documentation of results from an SRA.  See also Schedule Risk Analysis (SRA).

Schedule Risk Assessment (SRA) – The process of performing a probabilistic risk assessment on a project schedule. This type of schedule assessment is based on using Monte Carlo simulations that incorporate “minimum,” “maximum,” and “most likely” estimates for task durations.

Schedule Status Reporting – Schedule status reporting describes where the schedule now stands (i.e., actual data).  This category of communication and reporting refers to a high-level snapshot in time and may include lists or graphical views of actual activity/milestone dates or activity/milestone counts, for example.  It does not include any analysis of schedule metrics, trends, comparisons to previous versions, or forecast projections.  Examples of Schedule Status and Progress Reports include:  Milestone Status Reports, Summary Schedule Reports, Health Check Status Reports, Critical Path Reports, Total Float Reports, Margin Reports, and Resource Leveling Reports.  Because status information is more useful when compared to previous versions, it is often combined with Schedule Progress Reporting.  See also Schedule Report.

Schedule Variance – (1) The difference between the baseline (or planned) schedule and actual current (or forecasted) schedule performance.  (2) A metric for the schedule performance derived from earned value data.  Calculation:  SV = BCWP – BCWS. A positive value is a favorable condition while a negative value is unfavorable. It may be expressed for a specific period of time or cumulative to date.  See also Variance

Schedule Work-off – A schedule metric that helps to answer the question of whether the forecast is realistic.  It identifies the number of events completed/started (or scheduled for completed/started) during a planning period that are more than 30 calendar days late compared to the total number of events completed/started in that calendar period.  The max value is 1.0.  Should be able to filter by activity and milestone.  Calculation:  Prior to “time now”:  % of activities completed each month that are more than 30 days late; After “time now”:  % of activities in the future that are forecasted to be more than 30 days late.

Scope of Work – The complete work effort necessary to accomplish a Program or project(P/p)’s objectives as identified in the P/p’s WBS, which facilitates the identification of specific planning packages and work packages as a basis for schedule activities. 

Sensitivity Analysis – An analytical technique used to measure the uncertainty in the output of a model relative to different sources of uncertainty in model inputs.  Varying the input parameters and evaluating the changes in the outputs enables an analyst to evaluate the relationship between the inputs and outputs (testing the model) and the effects of those variations on the conclusions derived from the model.  Also known as “what if” analysis, sensitivity analysis can be used to understand different risk scenarios when performing an SRA/ICSRA, for example. 

Simulation – The imitation of a real-world process or system over time. The initial step requires the development of a mathematical model that represents key characteristics or behaviors of the system or process over time.

Slack – See Float.

Soft Constraint – A type of constraint that allows the logic to drive the schedule (i.e. restricts only movement to the left) on the constrained task.   Soft constraints include the following:

  • As Soon As Possible (ASAP).  An Activity or Milestone will finish as early as possible based on its assigned logical relationships and duration.  This condition can also be described as the absence of any constraint.
  • As Late As Possible (ALAP).  An Activity or Milestone will finish as late as possible without affecting the schedule end date.  It is a highly recommended practice that when using MS Project this constraint never be used.  This constraint uses total float to calculate its early finish date instead of free float.  This can cause the Program or project end date to slip. This constraint is not useful for Monte Carlo simulation since if any activity takes longer in some iteration it may just start earlier, which is illogical since it has usually already started before it is known to be taking longer.
  • Start No Earlier Than (SNET) or Start On or After.  An Activity or Milestone will start no earlier than the assigned start date.  However, it can start as late as necessary.  This constraint is often used to phase the activities such that they align with budget allocation.  Sometimes they are also used to align the activities with the availability of a facility.
  • Finish No Earlier Than (FNET) or Finish On or After.  An Activity or Milestone will finish no earlier than the assigned finish date.  However, it can finish as late as necessary.

See also Constraint and Hard Constraint.

Software Cost Estimating – An effort requiring identical processes as the estimation of hardware, utilizing different measures and tools. 

Space Act Agreement (SAA) – The National Aeronautics and Space Act of 1958 (herein, the Space Act) as amended (51 U.S.C. 20113(e)) authorizes NASA “to enter into and perform such… other transactions as may be necessary in the conduct of its work and on such terms as it may deem appropriate, with any agency or instrumentality of the United States, or with any state, territory, or possession, or with any political subdivision thereof, or with any person, firm, association, corporation, or educational institution.” 

Stakeholder – An individual or organizational customer having an interest (or stake) in the outcome or deliverable of a project. 

Standing Review Board (SRB) – The board responsible for conducting independent reviews (life cycle and special) of a project and providing objective, expert judgments to the convening authorities. The reviews are conducted in accordance with approved ToR, life-cycle requirements in NPR 7120.5, entrance and success criteria in NPR 1723.1, and maturity matrices in the NASA Space Flight Program and Project Management Handbook (NASA/SP-2014-3705). 

Start Date – The date that an activity is predicted (or permitted) to start, based on the current calculation of the schedule.  There are four types of start dates:  Early Start Date, Late Start Date, Expected (Planned) Start Date, and Actual Start Date

Statement of Work (SOW) – A document that contains a narrative description of the work scope requirements for a Program/ project or contract.

Status Date – The date up to which progress is included into a schedule update.  It defines the demarcation between actual work performed and remaining work.  It is also known as the update, data, “time now”, or “as of” date).  All dates “to the left” of the status date are considered by the scheduling tool to be “in the past”.  All dates “to the right” of the status date are considered by the scheduling tool to be “in the future”.  See also Time Now Date.

Statusing – The process of updating a schedule with actual dates, logic, and progress.  When a Program or project schedule is statused, the scheduling tool will adjust the forecast of the remaining effort.

Stochastic Critical Path – The path most likely to delay the Program or project after an SRA has been run, through which uncertainty and risks have been applied to the schedule.  Schedule simulation software identifies these paths using the risk criticality analysis that computes the number of iterations in which the activity is on the critical path divided by the total number of iterations conducted.  Interestingly, the risk-critical path may not be the same as the critical path as identified in the CPM schedule before risk and uncertainty are applied.  It is also referred to as the Probabilistic Critical Path or the Risk-Informed Critical Path.  See also Critical Path and Driving Path.

Successor – An activity or milestone that must follow either partially or entirely another task.

Summary Activity – The roll-up of a series of directly related activities within the schedule’s coding structure into one “summary” activity that illustrates the overall time required by the series of activities.

Summary Schedule – A high-level roll-up of the IMS and is used for management reporting.  It is a direct derivative of the IMS and should mimic the critical paths within the IMS.  See also Integrated Master Schedule (IMS), Intermediate Schedule, and Detailed Schedule.

Suppliers – Each project office is a customer having a unique, multi-tiered hierarchy of suppliers to provide it products and services. A supplier may be a contractor, grantee, another NASA Center, university, international partner, or other government agency. Each project supplier is also a customer if it has authorized work to a supplier lower in the hierarchy. 

Return to Top

T

Tailoring – The process used to adjust or seek relief from a prescribed requirement to accommodate the needs of a specific task or activity (e.g., project). The tailoring process results in the generation of deviations and waivers depending on the timing of the request. 

Task – See Activity.

Task Agreement (TA) – A written document describing the relationship between entities and scope of work each is responsible for accomplishing.

Task-Driven Activity – An activity for which duration is dependent upon a fixed amount of time to complete the work regardless of the amount of resources assigned.

Technical Critical Path – A path identified by the Program or project that is composed of high-risk technical activities that are presumed to be “critical.”  (Note:  The technical critical path may not be the deterministic critical path or the probabilistic critical path; an SRA should be run to confirm whether or not the technical critical path might in fact be critical.)

Technical Lead – Individual with the assigned responsibility of accomplishing the work contained in each WBS element to comply with the SMP.  Technical Leads are accountable for the development, execution, and control of their work scope within the IMS, and therefore need to coordinate with the Program or project Planner/Scheduler to ensure that the schedule reflects accurate information, updated in a timely manner.  (Also includes WBS Element Owner/Control Account Manager (CAM)/Integrated Product Team (IPT) Lead.)

Technology Readiness Level (TRL) – A common scale that describes the maturity of a technology, which is utilized as an input planning development efforts.  Many cost and schedule estimation models utilize TRL as an input parameter. 

Termination Review – A review initiated by the Decision Authority for the purpose of securing a recommendation as to whether to continue or terminate a project. Failing to stay within the parameters or levels specified in controlling documents will result in consideration of a termination review.

Terms of Reference (ToR– A document specifying the nature, scope, schedule, and ground rules for an independent review or independent assessment. 

Then Year (TY) Dollars – The values associated with costs or estimates in the year that they are planned or occur, also called RY dollars. These costs include any projected or experienced inflation, as opposed to CY dollars, which provide total costs from a cash flow in a single-year base (deflated or inflated). 

Threats – Events that may have a negative impact on project cost, schedule, or technical performance. Project funds or UFE are not yet allocated to its mitigation. 

Time Dependent (TD) Costs – Costs that are a function of activity duration multiplied by the periodic value (burn-rate).  If the schedule is longer than planned, additional costs will be incurred; if the schedule is shorter than planned then less costs will be incurred.  Examples of time dependent costs include labor (i.e., indirect costs represented by level of effort (LOE) activities, direct costs sometimes called the “marching army”, or full-time equivalent (FTE)/whole time equivalent (WYE)) costs, typically found in Program or project management, systems engineering, or safety and mission assurance activities, as well as rent, utilities, facility maintenance, equipment rental, sustaining operations, or any other costs that are charged by the amount of time they are employed.  In addition to being affected by time, the burn rate is an estimate so it may be affected by risks and uncertainty, independent of the total duration of the activity.  See also Time Independent (TI) Costs.

Time Impact Analysis – A schedule analysis method that involves the insertion or addition of activities indicating delays or changes into an updated schedule representing progress up to the point when a delay event occurred to determine the impact of those delay activities.  Time impact analysis can be used in conjunction with Analysis of Alternatives (AoA) or Schedule Risk Analysis (SRA), but on its own is not a robust method for understanding schedule forecasts. 

Time Independent (TI) Costs – Costs that are fixed, irrespective of overall task duration.  In other words, TI cost does not grow because of an increase in schedule duration.  Examples of TI costs include procurements of components, materials, or even a set service, in addition to tests and other expenses.  If these costs have not fully occurred, the cost-to-completion may be uncertain or influenced by uncertainty or discrete risks, but not be the duration of the activities to which it is assigned.  See also Time Dependent (TD) Costs.

Time-Phased Cost – Costs that have been allocated to a schedule or time period. 

Time Now – See Status Date

Time Units – The defined unit of measurement according to which the activity durations are scheduled (e.g., hours, days, weeks, etc.).

Time Value of Money – The value of money including a given amount of interest earned over a given amount of time. This core concept in financial analysis enables the calculation of present value and its derivatives. 

To Complete BEI – Identifies number of events remaining (finish or start) to the number of events that were baseline planned for the future. Values range for 0.0 to infinity.  Should be able to filter by activity and milestone.

To Complete Performance Index (TCPI) – The future cost efficiency needed to accomplish the remaining work within a financial goal such as the Budget at Completion (BAC) or the Estimate at Completion (EAC). It compares the budget for remaining work with the remaining cost or the estimated remaining cost to complete the work. TCPIBAC = (BAC – BCWP cum) / (BAC – ACWP cum). Or TCPIEAC = (BAC – BCWP cum) / (EAC – ACWP cum). Compare the CPI to determine if the BAC or the EAC is realistic or not. 

Top-Down Estimating – An estimating technique that stems from Program or project (P/p) requirements and produces an estimate from an overall P/p perspective or by P/p phase.  Top-down estimates are less robust than other estimates because they do not consider lower-level details; however, they often require less P/p staff involvement to produce.  Types of top-down estimating include:  Analogous EstimatingEstablished Standards Estimating, Extrapolation, Expert Experience and Judgement Estimating, Parametric Estimating, and Probabilistic Estimating.  See also Schedule Estimate.

Total Allocated Budget (TAB) – The sum of all budgets allocated to a project/contract. Total allocated budget consists of the PMB and all MR. The TAB should reconcile directly to the PBB/CBB. If the TAB is greater than the CBB/PBB, the difference is attributable to an over target baseline and must be documented. 

Total Cost of Ownership (TCO) – The total cost of an investment over a life cycle, including development, operations, maintenance, upgrades, and decommissioning. 

Total Float – The amount of time a task may slip before impacting Program or project (P/p) completion (or the end date of a schedule).  Positive Total Float is an indication that an activity can be delayed without affecting the P/p completion.  Negative Total Float is an indication that an activity will impact the P/p completion unless the time is recovered.  Zero Total Float is an indication that an activity delay of a given number of days will result in a P/p delay of the same number of days.  See also Float (Slack).

Trade Study – The techniques utilized to compare alternatives as part of the decision to select the preferred alternative(s). These studies may range from formal Analyses of Alternatives (AoA) to informal quantitative analyses. 

Return to Top

U

Unallocated Future Expense (UFE) – The portion of estimated cost required to meet specified joint confidence level (JCL) that cannot yet be allocated to the specific Program or project WBS sub-elements because the estimate includes probabilistic risks and specific needs that are not known until these risks are realized.   In other words, it is the funding that is provided to accommodate the realization of risk and uncertainty associated with a cost or schedule estimate.  These funds may ultimately be distributed to mitigate the risk, to make the product work, or to accommodate cost or schedule growth, but, because not all risks or uncertainties will be realized, initial allocation of funds to particular WBS elements would be premature. UFE is established by exercising probabilistic techniques. 

Uncertainty – The indefiniteness about a Program or project(P/p)’s baseline plan.  It represents the fundamental inability to perfectly predict the outcome of a future event.  As distinct from known risks, uncertainty has a probability of occurring of 100%, although the level of uncertainty may differ for different phases of the P/p such as engineering, construction, procurement, testing, or commissioning.  Uncertainty is characterized by a probability distribution (e.g., uniform, triangular, betaPERT, etc.) that utilize schedule parameters (e.g., three-point estimate), which are based on a combination of the prior experience of the Schedule Analyst and/or Technical Lead, historical data, and actual P/p performance.  Uncertainty includes estimating error, estimating bias if any, and inherent unexplained variability of the P/p work.  It does not represent the impact of discrete risks. See also Risk. 

Undistributed Budget (UB) – Budget applicable to task order effort that has not been identified to lower level WBS elements. 

Unfunded Schedule Margin – A margin activity for which funding has not explicitly been set aside by the Program or project (P/p) to cover anticipated costs.  The use of margin will likely, eventually require funding; however, it is possible that funding needed (i.e., Management Reserve) to employ the margin task and absorb the risk impact or mitigation is not managed at the P/p level and will need to come from NASA HQ-held Unallocated Future Expenses (UFE).  Because UFE is generally risk-informed as part of a risk analysis exercise to set the Agency Baseline Commitment (ABC), it is likely that UFE will exist in an amount to cover the projected risks that may affect the schedule.  See also Schedule Margin and Funded Schedule Margin.

Usage Variance (UV) – For material analysis, UV = (Budget Quantity – Actual Quantity)) x (Budgeted Price). Quantity breakouts most useful on programs procuring multiple items of the same part number, typical for production type contracts. 

Return to Top

V

Validity – A property of the Program or project schedule that indicates it is logically sound.  Schedule validity is tested using the Compliance Test and Critical Path Analysis Test as part of Schedule Assessment.

Value Engineering – A systematic effort to improve the value of goods or services utilizing an examination of the function. Value can be increased by either improving the function or reducing cost while preserving basic functions. 

Variable Cost – Costs that change in proportion to the activity of the effort. The concept is useful in forecasting the impact of performance when planned baselines are not achieved. 

Variance – (1) For general schedule reporting purposes, the difference between the baseline (or planned) and current actual (or forecasted) performance that requires further review, analysis, or action.  Appropriate thresholds are established in advance as to the magnitude of variance that will require formal variance analysis.  See also Schedule Variance.  (2) In EVM, Schedule Variance (SV) compares Earned Value (EV) to Planned Value (PV), Calculation:  SV = EV-PV; and Cost Variance (CV) compares Earned Value (EV) to Actual Cost (AC), Calculation:  CV = EV- AC. 

Variance Analysis – (1) A quantitative analysis of the difference between actual and planned behavior in the schedule (e.g., planned start/finish date vs. actual start/finish date).  (2) In EVM, Variance Analysis is a Monthly Deliverable (IPMR Format 5) that describes a root cause, impact and corrective action of top cost, schedule, and at-completion variances, among other items.  See Integrated Program Management Report

Variance Analysis Report (VAR) – A report that explains variances that exceed specified thresholds which are reportable. Explanations of variances shall clearly identify the nature of the problem, significant reasons for cost or schedule variances (i.e., root cause), effects on immediate tasks, impacts on the total contract, and the corrective actions taken or planned. 

Variance at Completion (VAC) – The difference between the budget at completion and the estimate at completion (VAC = BAC – EAC). It may be calculated at any level from the Control Account up to the total project/contract. It represents the amount of expected overrun (negative VAC) or underrun (positive VAC).

Vertical Traceability – A demonstration that the schedule is a hierarchical, tiered network capable of rolling up to high-level summary representations of activities, as well as breaking down to the lowest level of task details showing dependencies, resources, durations, and constraints.

Return to Top

W

Waiver – A documented authorization releasing a project from meeting a requirement after the requirement is put under configuration control at the level the requirement will be implemented. 

What-If Analysis – See Sensitivity Analysis.

Work – See Effort

Work Authorization Document (WAD– A form used to document authorized and budgeted work from the Project Manager or sub-project/element manager. As a minimum this document must include the relevant WBS Control Account code, SOW, scheduled start and completion dates, budget, and the name of the P CAM. 

Work Breakdown Structure (WBS) – A product-oriented hierarchical division of the hardware, software, services, and data required to produce the program’s or project’s end product(s), structured according to the way the work will be performed and reflecting the way in which program/project costs and schedule, technical, and risk data are to be accumulated, summarized, and reported. 

WBS Dictionary – A document that describes the definition and content of each activity associated with each WBS element, in product-oriented terms, and relates each element to the respective, progressively higher levels of the WBS as well as to the Statement of Work, if applicable. 

WBS Element – Any block or unique entry in a work breakdown structure regardless of level. 

WBS Levels – The arrangement or configuration of a WBS which establishes the hierarchy of projects to programs, systems to projects, subsystems to systems, etc. 

Workforce – The people resources assigned to do work.  See also Resource.

Work Package (WP) – A segmented portion of discrete Program or project scope within a Control Account that is broken down into logically linked activities in the schedule.  A work package has the following characteristics:

  • Represents unit of work at the level where work is performed.
  • Clearly separate from other Work Packages.
  • Assignable to a single organizational element.
  • Has scheduled start and completion dates, and interim milestones – if required- all of which represent physical accomplishment.
  • Has budget expressed in terms of dollars or hours/FTEs.
  • Its duration is limited to a relatively short span.
  • Is integrated with detailed engineering, shop, or other schedules.
  • Has a correct Performance Measurement Technique assigned to it.

For P/ps that require EVM, performance is measured against work packages.  See also Planning Package (PP)

Wrap Rate – In NASA cost estimating language, major relatively fixed-cost components such as project management, systems engineering, and safety and mission assurance are referred to as wraps. The components of the wrap rate will vary from model to model. In many parametric cost models, the cost of these elements is calculated as a function of the cost of the hardware and software. 

Return to Top