PERT Estimation Method

Study Notes

Estimating Techniques

PERT (Program Evaluation and Review Technique) is a more accurate estimating method than the triangular estimate.
PERT three-estimates is the most applied estimating method by project managers.

Triangular Distribution

Calculation: (P + ML + O) / 3
P: Pessimistic duration, ML: Most Likely duration, O: Optimistic duration

Learning Curves

The learning effect: Time per repetition decreases as the number of repetitions increases

Standard Time and Stopwatch Time Study

Standard time: The time it should take a fully trained and qualified worker to complete a specific task, working at an efficient, yet sustainable pace.
Observed time: The average of recorded times.
Normal time: Observed time adjusted for worker performance, calculated by multiplying observed time by a performance rating (NT = OT * PR).
Standard time: Normal time multiplied by an allowance factor for personal delays, unavoidable delays, and breaks (ST = NT * AF).

Stopwatch Time Study

Example: Observed time 5 hours, normal time 6 hours, idle time 25%, standard time 7.5 hours (6 * (1 + 0.25)).

Three-Point Estimate

Optimistic time: Minimum time required to accomplish an activity, assuming things will go better than normally.
Pessimistic time: Maximum possible time required to accomplish an activity, assuming everything that can go wrong, will do.
Most likely time: Best time estimation of the accomplishment of an activity, assuming everything goes as expected.
Expected time: Best estimation of the time needed to accomplish an activity, taking into account that complications might appear, calculated using the formula (P + 4ML + O) / 6.

Parametric Estimates

Example: Resource Units/day = WBS Effort Hours / Resource Working Hours/day * % Availability
Duration (days) = Work / Resource Units

Description

This quiz covers the PERT technique, a method used for estimating project tasks, which has been tested across various industries and countries. It also explores the triangular distribution formula used in PERT.