Which network schedule uses three time estimates?

Which network schedule uses three time estimates?

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

Answer: (D)

Three time estimates are used to model uncertainty in activity durations, a hallmark of PERT. In this approach, each activity has an optimistic, most likely, and pessimistic duration. These three numbers feed into a probability-based timing calculation, commonly te = (a + 4m + b)/6, to produce an expected duration that reflects the uncertainty in how long the activity will take. This allows you to estimate the overall project duration and the probability of meeting a deadline, as well as identify which activities most affect the schedule (the critical path) under uncertainty. Other network scheduling methods typically use a single fixed duration for each activity and don’t incorporate this three-estimate, probabilistic approach, and a Gantt chart is mainly a visual timeline rather than a probabilistic model. So the use of three estimates points to PERT.

Three time estimates are used to model uncertainty in activity durations, a hallmark of PERT. In this approach, each activity has an optimistic, most likely, and pessimistic duration. These three numbers feed into a probability-based timing calculation, commonly te = (a + 4m + b)/6, to produce an expected duration that reflects the uncertainty in how long the activity will take. This allows you to estimate the overall project duration and the probability of meeting a deadline, as well as identify which activities most affect the schedule (the critical path) under uncertainty. Other network scheduling methods typically use a single fixed duration for each activity and don’t incorporate this three-estimate, probabilistic approach, and a Gantt chart is mainly a visual timeline rather than a probabilistic model. So the use of three estimates points to PERT.