Which network schedule uses only one time estimate?

Which network schedule uses only one time estimate?

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

Answer: (D)

In a network schedule, some methods assume a fixed, single duration for each activity, making the plan deterministic. The Arrow Diagram Method embodies this approach: activities are drawn as arrows between events, and each arrow carries one duration value. Because there’s no built-in uncertainty, you only need one time estimate for each activity, and the schedule can be analyzed with a straightforward forward pass to find early start/finish and a backward pass to find late start/finish and slack. In contrast, the Technique that accounts for uncertainty uses three time estimates—optimistic, most likely, and pessimistic—to derive an expected duration, reflecting variability in how long tasks might take. Gantt charts visualize the timeline and can use single estimates, but they are not the network diagram method itself. So the network schedule that uses only one time estimate is the Arrow Diagram Method.

In a network schedule, some methods assume a fixed, single duration for each activity, making the plan deterministic. The Arrow Diagram Method embodies this approach: activities are drawn as arrows between events, and each arrow carries one duration value. Because there’s no built-in uncertainty, you only need one time estimate for each activity, and the schedule can be analyzed with a straightforward forward pass to find early start/finish and a backward pass to find late start/finish and slack.

In contrast, the Technique that accounts for uncertainty uses three time estimates—optimistic, most likely, and pessimistic—to derive an expected duration, reflecting variability in how long tasks might take. Gantt charts visualize the timeline and can use single estimates, but they are not the network diagram method itself. So the network schedule that uses only one time estimate is the Arrow Diagram Method.