HKSM
Activity Duration Estimates
Numerical predictions of how many time units (e.g., hours, days, weeks) are expected to be needed to finish an activity.
Key Points
- Expressed as single-point values or ranges (e.g., three-point estimates using optimistic, most likely, and pessimistic figures).
- Based on scope details, resource availability and productivity, calendars, assumptions, and identified risks.
- Different from effort: effort is work required, while duration reflects elapsed time considering resource allocation and constraints.
- Feeds the schedule model and critical path analysis and is refined as better information becomes available.
Example
A development task is estimated at 16 hours of effort. With one developer available at 50% capacity on an 8-hour workday, the activity duration is estimated at about 4 working days. Using three-point estimating, the team records 3–5 days with key assumptions and risks noted.
PMP Example Question
Which output represents the numeric forecast of how many time periods will be needed to complete a scheduled task?
- Work performance data
- Activity duration estimates
- Reserve analysis
- Effort hours
Correct Answer: B — Activity duration estimates
Explanation: Activity duration estimates quantify the expected number of time periods to finish an activity; they are used to build and update the project schedule.
