Which project scheduling technique uses probabilistic time estimates?

Which project scheduling technique uses probabilistic time estimates?

• A. Gantt Chart
• B. Program Evaluation and Review Technique (PERT)
• C. Critical Path Method (CPM)
• D. Forward Pass

Answer: (B)

Probabilistic time estimates come from modeling uncertainty in activity durations. The Program Evaluation and Review Technique (PERT) uses three-point estimates—optimistic, most likely, and pessimistic—to derive an expected duration and the variability of each activity. This approach lets you calculate the overall project completion probability and assess schedule risk, rather than locking in a single fixed date. Gantt charts primarily visualize the schedule with bars showing start and finish dates, but they don’t inherently incorporate uncertainty or probability. CPM relies on fixed, single-point time estimates and deterministic calculations to find the critical path and earliest and latest times through a forward and backward pass, without modeling randomness. The forward pass itself is just a step in CPM to determine earliest times, not a probabilistic method.

Probabilistic time estimates come from modeling uncertainty in activity durations. The Program Evaluation and Review Technique (PERT) uses three-point estimates—optimistic, most likely, and pessimistic—to derive an expected duration and the variability of each activity. This approach lets you calculate the overall project completion probability and assess schedule risk, rather than locking in a single fixed date.

Gantt charts primarily visualize the schedule with bars showing start and finish dates, but they don’t inherently incorporate uncertainty or probability. CPM relies on fixed, single-point time estimates and deterministic calculations to find the critical path and earliest and latest times through a forward and backward pass, without modeling randomness. The forward pass itself is just a step in CPM to determine earliest times, not a probabilistic method.