PMI-SP Duration Estimating 4 — Questions and Answers
Question 1: A project has an activity with a most optimistic duration of 6 days, most likely of 10 days, and most pessimistic of 14 days. What is the standard deviation of this activity's duration?
- 1.0 days
- 1.33 days (Correct answer)
- 2.0 days
- 2.67 days
Correct answer: 1.33 days
Standard deviation = (P - O) / 6 = (14 - 6) / 6 = 8 / 6 ≈ 1.33 days.
Question 2: Which tool in the Estimate Activity Durations process helps account for the effect of risks on overall project schedule duration?
- Resource breakdown structure
- Reserve analysis (Correct answer)
- Precedence diagramming method
- Schedule network analysis
Correct answer: Reserve analysis
Reserve analysis adds contingency reserves to account for schedule risks and buffer the project against identified uncertainties.
Question 3: A scheduling professional notes that resource productivity varies significantly across a global team due to varying skill levels. Which technique BEST handles this variability in duration estimates?
- Analogous estimating using one regional team's data
- Parametric estimating with fixed productivity rates
- Three-point estimating using optimistic, likely, and pessimistic values (Correct answer)
- Single-point estimating from the project manager
Correct answer: Three-point estimating using optimistic, likely, and pessimistic values
Three-point estimating captures variability through optimistic, most likely, and pessimistic estimates, making it ideal for handling skill-level differences.
Question 4: A project manager is updating duration estimates after scope changes in the middle of the project. Which estimating approach is MOST appropriate at this stage when detailed information is now available?
- Analogous estimating
- Rough order of magnitude
- Bottom-up estimating (Correct answer)
- Delphi technique
Correct answer: Bottom-up estimating
Bottom-up estimating is most appropriate when detailed scope information is available, as it builds estimates from individual work packages upward.
Question 5: Which of the following BEST describes the relationship between resource units and activity duration?
- Increasing resources always decreases duration proportionally
- Duration is independent of the number of resources assigned
- Adding resources can reduce duration, but not always linearly due to coordination overhead (Correct answer)
- Fewer resources always result in higher quality outputs
Correct answer: Adding resources can reduce duration, but not always linearly due to coordination overhead
Adding more resources can reduce duration, but coordination overhead and diminishing returns mean the reduction is rarely proportional.
Question 6: A PMI-SP candidate is reviewing activity duration estimates developed by team leads. The estimates seem consistently high across all activities. What technique should the scheduler apply to validate and possibly compress these estimates?
- Monte Carlo simulation (Correct answer)
- Reserve analysis
- Leads and lags adjustment
- Schedule compression through crashing
Correct answer: Monte Carlo simulation
Monte Carlo simulation can validate estimates by modeling the probability distribution of completion dates and exposing excessive conservatism.
Question 7: When collecting duration estimates, a project manager uses the Delphi technique. What is the PRIMARY benefit of this approach?
- It produces parametric equations for future use
- It eliminates the need for subject matter experts
- It reduces group bias and anchoring by anonymizing expert input (Correct answer)
- It requires only one round of estimation to finalize durations
Correct answer: It reduces group bias and anchoring by anonymizing expert input
The Delphi technique anonymizes responses across rounds, reducing the influence of dominant voices and minimizing anchoring and group-think bias.
PMI-SP Duration Estimating 4
A project has an activity with a most optimistic duration of 6 days, most likely of 10 days, and most pessimistic of 14 days.
What is the standard deviation of this activity's duration?