AACE PRMP common mistakes
AACE PRMP · Understand the traps and how to avoid them.
Identifies the critical path by the chain with the largest sum of activity durations or by the path with the most activities, rather than by the longest path through the logic network and the resulting zero-total-float path.
Duration totals are easy to eyeball, and many candidates carry over a simplified definition of critical path from introductory scheduling; calendars, constraints, and lags make a simple duration sum unreliable.
What to do instead
Perform a forward and backward pass, compute total float for every activity, and identify the longest path through the logic. Verify the result against calendar assignments, constraints, and lags, and test whether removing a constraint changes the path before reporting it.
Forces contract or target milestone dates by applying start-no-earlier-than and finish-no-later-than constraints instead of building the logic or adjusting scope, then reports the resulting schedule as if it were logic-driven.
There is pressure to show compliance with fixed dates, and constraints are a fast software fix; candidates often forget that constraints can mask negative float and distort the critical path.
What to do instead
Use logic ties to drive dates whenever possible. When an external date must be fixed, document it as a constraint, run a constraint and negative-float check, report the exposed negative float, and obtain approval for the date basis.
Uses lags, such as a 10-day lag for submittal review or concrete curing, as a substitute for actual activities and then ignores how the lag calendar affects float and the critical path.
Lags are quick to enter and do not require creating activities, but candidates often forget that lags can span calendars differently and can hide missing logic.
What to do instead
Model substantive work as activities with duration and resources. For necessary lags, assign the correct calendar, document the rationale in the schedule basis, and test the schedule's sensitivity to changes in lag duration.
Accepts out-of-sequence progress by entering actual start dates for successor activities while leaving the original finish-to-start logic intact, without deciding between retained logic and progress override.
Field updates frequently show successors starting before predecessors finish, and scheduling software defaults can make the choice invisible; candidates focus on entering dates rather than on the method's effect on remaining work.
What to do instead
Choose retained logic or progress override deliberately, document the choice in the schedule basis, correct illogical ties, and review the critical path and remaining durations after each update.
Calculates percent complete for a long-duration activity from elapsed duration, for example treating 50 percent of the days passed as 50 percent physical progress, even when the work is front-loaded or back-loaded.
Duration-based percent complete is readily available in scheduling software, and candidates confuse elapsed time with earned progress; this overstates progress on activities with non-linear work.
What to do instead
Define measurement rules in the schedule basis and use weighted milestones, units, or earned value for non-linear activities. Reconcile schedule progress with cost and earned value data before reporting.
Uses a summary-level schedule such as a Level 1 or Level 2 schedule to evaluate detailed delay or resource conflicts, or uses a detailed execution schedule as the executive report.
All schedule levels can look similar in software, and candidates often do not connect each level to its intended audience and decision purpose.
What to do instead
Map schedule levels to their purpose: summary levels for management communication, execution levels for control, and detailed levels for analysis. Roll up detail for reporting and use the appropriate detailed schedule for delay or resource analysis.
Omits or treats as optional the schedule basis document, then cannot defend calendars, lags, constraints, resource assumptions, progress measurement rules, or reporting conventions.
Candidates concentrate on drawing the network and treat the basis as paperwork, but many exam scenarios test whether assumptions are documented and traceable.
What to do instead
Prepare the schedule basis early and update it with each revision. Include scope, assumptions, calendars, logic and lags, constraints, resource assumptions, risks, progress rules, and reporting requirements.
Confuses the cost-based schedule performance index, SPI = EV/PV, with the time-based earned schedule index, SPI(t) = ES/AT, or reports a schedule variance in dollars when the question asks for schedule variance in time.
The metrics have similar names and are often taught together, and candidates may carry over cost earned value terminology without separating schedule performance in time from schedule performance in cost.
What to do instead
Define each metric explicitly. Compute earned schedule and use SPI(t) = ES/AT and SV(t) = ES minus AT for time-based schedule performance, labeling cost-based and time-based metrics separately in reports.
Performs a time impact analysis by adding the claimed delay to the end of the as-built schedule or by inserting it into a schedule that already contains other delays, without establishing a contemporaneous window and cause.
Adding delay to the end is simpler than selecting a pre-delay updated schedule and inserting the delay prospectively, and candidates often overlook the method's requirement to isolate causation.
What to do instead
Use a prospective time impact analysis: select the updated schedule before the delay event, insert the delay activity and logic, run the CPM, and compare completion dates. Document the window, the event, and causation, and use a consistent accepted delay analysis method.
Reports total float from the baseline schedule rather than from the current updated schedule when communicating near-critical status, or reports a single float value without stating the data date and constraint basis.
Baseline float is often readily available and looks authoritative, but it does not reflect current logic, progress, or constraints; candidates may also omit the data date that gives float meaning.
What to do instead
Report total float from the current update, state the data date, and distinguish baseline float from current float. Note any constraints or calendars that affect float so the audience can interpret near-critical status correctly.