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PMP Practice: Modify schedule as needed based on methodology

Question 5 of 5 in Plan and Manage Schedule

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Ash Tanaka is managing a municipal water treatment facility upgrade for Cedar Tanaka Authority. The project uses a predictive approach with a 14-month timeline. During schedule planning, the engineering team provides optimistic duration estimates of 8 weeks for the filtration system installation, while the procurement lead warns that specialized components historically take 12-16 weeks to arrive due to custom manufacturing requirements. The construction supervisor suggests 10 weeks is realistic if weather cooperates. Ash needs to finalize the schedule baseline for stakeholder approval next week. The project charter explicitly states that missing the regulatory compliance deadline will result in daily fines of $50,000. What should Ash do to establish the most credible schedule baseline?
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Correct answer: Apply a three-point estimation technique using the optimistic, pessimistic, and most likely durations to calculate expected duration

Explanation

When facing conflicting duration estimates with significant variance, particularly in a high-stakes predictive project with regulatory penalties, the project manager should use a structured estimation technique that incorporates uncertainty. Three-point estimation uses optimistic, pessimistic, and most likely values to calculate a weighted expected duration, providing a more statistically sound baseline than selecting one estimate or simply averaging. This approach acknowledges the range of uncertainty while producing a defendable, probabilistic estimate appropriate for the schedule baseline. Given the regulatory deadline and financial penalties, the schedule must be both credible and realistic. The scenario provides three distinct estimates with different assumptions, making this the ideal situation for three-point estimation. This produces a more accurate expected value while also enabling the PM to calculate schedule confidence levels and contingency reserves based on the estimate variance.

**Why not A:** Scheduling the activity at 16 weeks (the pessimistic estimate) builds excessive buffer into the baseline. While it ensures the activity will not overrun, it artificially extends the project schedule and may misallocate resources by padding a single activity rather than applying a statistically justified estimate.

**Why not B:** Simply averaging the three estimates gives equal weight to optimistic, most likely, and pessimistic values. Three-point estimation applies a weighted formula (typically PERT: O + 4M + P / 6) that gives more weight to the most likely estimate, producing a statistically more defensible expected duration than a simple average.

**Why not C:** Using the engineering team's 8-week optimistic estimate as the baseline creates unrealistic expectations. With $50,000 daily fines for missing the regulatory deadline, basing the schedule on the most favorable scenario ignores procurement lead time warnings and construction weather dependencies, significantly increasing the risk of deadline penalties.

Key Concept

This question covers Modify schedule as needed based on methodology under Plan and Manage Schedule (Process).

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