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Program Evaluation and Review Technique (PERT)

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The Program Evaluation and Review Technique (PERT) is a statistical tool used to model the tasks involved in completing a project, particularly when time estimates are uncertain. PERT uses probabilistic time estimates to calculate the expected duration of each activity and the overall project. It involves three-time estimates for each task: optimistic (the shortest time in which the activity can be completed), most likely (the completion time having the highest probability), and pessimistic (the longest time the activity might take). By applying these estimates, PERT calculates the expected time for each task using the formula: (Optimistic + 4×Most Likely + Pessimistic) ÷ 6. This approach acknowledges the inherent uncertainty in project scheduling and provides a more realistic timeline. PERT charts visually represent task sequences and dependencies, helping project managers to identify the critical path and analyze the time variability within the project schedule. This technique is particularly useful in research and development projects where activity durations are difficult to predict. By incorporating the variability and risk of time estimates, PERT enhances the planning and decision-making process, enabling project managers to anticipate potential delays and implement contingency plans. It ultimately contributes to more effective schedule development by providing a probabilistic assessment of project completion times.

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Question 1

When conducting PERT estimations, what is the primary benefit of using three-point estimates?

Correct Answer: It accounts for uncertainty through optimistic, most likely, and pessimistic scenarios

The primary benefit of three-point estimates in PERT (Program Evaluation and Review Technique) is that it incorporates uncertainty by considering three different scenarios: optimistic, most likely, and pessimistic durations for each activity. This approach provides several advantages: 1. Better risk assessment by considering multiple scenarios 2. More realistic estimates by accounting for variability 3. Improved accuracy through weighted calculations 4. Enhanced stakeholder confidence due to comprehensive analysis Why other answers are incorrect: - Using weighted averages of past project timelines alone doesn't account for unique project characteristics and future uncertainties - Statistical regression models and benchmarking are different estimation techniques that don't specifically address uncertainty in the way three-point estimates do - Combining expert judgment with parametric estimating is a different methodology that doesn't specifically account for the range of possible outcomes like three-point estimates do.

Question 2

In a PERT diagram, when activities have multiple parallel paths, which path should receive the most attention from the project manager?

Correct Answer: The path with the longest duration and least float time

The critical path (the path with the longest duration and least float time) requires the most attention from project managers because: 1. It determines the overall project completion date 2. Any delay on this path will delay the entire project 3. There is minimal or no slack time to accommodate delays 4. It represents the sequence of activities that must be completed on schedule Why other options are incorrect: The number of sequential activities alone doesn't determine criticality - what matters is the total duration and float time. While high-risk activities and resource requirements are important considerations, they may not be on the path that determines the project's completion date. The number of milestones and stakeholder touchpoints, though important for tracking progress, doesn't necessarily indicate the path requiring most attention from a scheduling perspective.

Question 3

In PERT analysis, what is the correct formula to calculate expected duration (Te)?

Correct Answer: Te = (O + 4M + P) / 6

In PERT (Program Evaluation and Review Technique) analysis, the formula Te = (O + 4M + P) / 6 is the correct way to calculate expected duration. This formula applies a weighted average where: - O = Optimistic duration (weight of 1) - M = Most likely duration (weight of 4) - P = Pessimistic duration (weight of 1) The most likely estimate (M) receives the highest weight (4) because it's considered the best estimate based on normal conditions. The optimistic (O) and pessimistic (P) estimates each receive a weight of 1, reflecting their lower probability of occurrence. This weighting creates a beta distribution, which is commonly used in project management for its ability to model skewed data. The divisor of 6 represents the sum of the weights (1 + 4 + 1 = 6) to maintain a proper weighted average. The other formulas provided are incorrect variations that would give inaccurate expected durations and do not properly represent the beta distribution used in PERT analysis.

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