AACE CST cheat sheet

The 100% rule requires that child WBS elements sum exactly to the parent's scope, with no overlap between siblings and no omitted work.

Activity duration formula: Duration = (Quantity of work) ÷ (Crew size × Productivity per unit), then converted to workdays using the assigned calendar.

Planning defines what work will be performed and how; scheduling applies logic, durations, and calendars to determine when it will be performed.

A milestone is a zero-duration activity representing a significant event or contractual date; it is not a work activity and carries no resources.

Hard (mandatory) constraints override network logic and can produce negative float; use them only when externally imposed, such as a contract milestone.

The schedule basis document records scope, assumptions, constraints, calendars, data sources, and software settings used to build the schedule.

Activity ID coding should be unique and structured so the schedule can be sorted and filtered by WBS, phase, discipline, responsibility, and location.

A resource-loaded plan assigns labor, equipment, and materials to activities; the resulting resource histogram drives leveling decisions.

Forward pass: ES = maximum predecessor EF plus lag; EF = ES + duration, with duration computed on the activity's assigned calendar.

Backward pass: LF = minimum successor LS minus lag; LS = LF − duration.

Total float = LS − ES = LF − EF; free float = minimum successor ES − EF.

The critical path is the longest logic path through the network; its length equals the shortest possible project duration.

Four relationship types: finish-to-start, start-to-start, finish-to-finish, and start-to-finish; finish-to-start is the default in most schedules.

Positive lag adds wait time between activities; negative lag (lead) overlaps them; lags should be justified and minimized.

Negative total float means the logic-driven finish is later than an imposed date; resolving it requires re-sequencing, crashing, or fast tracking.

An open end is an activity lacking a predecessor or successor; excessive open ends reduce logic validity and can hide the true critical path.

The baseline is the approved, frozen schedule; any change to it must pass through formal change control and be re-approved.

The data date (status date) separates recorded actuals from forecast work; all remaining durations are scheduled forward from this date.

Remaining duration is the work time still needed from the data date; duration percent complete = (original duration − remaining duration) ÷ original duration.

Out-of-sequence progress occurs when a successor starts before its predecessor finishes; it must be resolved using retained logic or progress override.

Retained logic preserves the original network logic during updates; progress override ignores logic to accommodate reported out-of-sequence work.

Schedule updates follow the contract-specified cycle, commonly monthly, and each update records progress, revised durations, and approved changes.

Actual start and actual finish dates are historical facts and are not moved by later updates; only remaining work is rescheduled.

A schedule log documents revisions, rationale, and approvals for each update to preserve an audit trail.

Schedule variance (SV) = BCWP − BCWS; a negative value indicates work is behind the baseline plan.

Schedule performance index (SPI) = BCWP ÷ BCWS; SPI below 1.0 indicates slippage, above 1.0 indicates ahead-of-plan progress.

Earned schedule converts earned value into time: ES is the date when BCWS equals BCWP, and SPI(t) = ES ÷ actual time.

Time impact analysis inserts a fragnet for the change or delay into the current schedule and measures the resulting movement of the completion date.

Windows analysis compares successive schedule updates over defined periods to apportion delay among parties retrospectively.

Float trend analysis compares baseline total float with current total float; declining float signals increasing schedule risk and reduced flexibility.

Common reports include the Gantt chart, network diagram, resource histogram, cash-flow S-curve, and critical path report.

Resource leveling shifts activities within their float to resolve peaks; if float is insufficient, the project completion date may extend.

Earned value terms: planned value (BCWS), earned value (BCWP), and actual cost (ACWP); all performance metrics derive from these three.

Cost variance = EV − AC; cost performance index = EV ÷ AC; CPI below 1.0 indicates cost overrun.

Estimate at completion = AC + (BAC − EV) ÷ CPI when current cost performance is expected to continue.

Estimate to complete = EAC − AC; variance at completion = BAC − EAC.

The WBS is the common framework linking scope, schedule activities, cost accounts, and earned value measurement.

A cost account is the control point where a WBS element meets an organizational unit; it is where budgets and earned value are managed.

Management reserve sits outside the performance measurement baseline for unidentified risks; contingency sits inside for identified risks.

Integrated change control evaluates scope, schedule, cost, and risk impacts before approving any change to the baseline.