Answers the Question
How much of a resource will be required to complete a project?
Calculator for PERT
What Is the PERT?
This formula, developed by the American Navy, was commonly used to estimate the time required for a task with several unknowns. There is no reason, however, that it can't also be used for estimating project costs - especially for projects in which time is a primary driver of project expense.
Why Is it Important?
- There are many unknowns that can affect project execution times and associated costs. Many models simply ignore them, but PERT adjusts its output to account for them.
Formula(s) to Calculate PERT
- ESTIMATE = (OPTIMISTIC ESTIMATE + (4 * MOST LIKELY ESTIMATE) + PESSIMISTIC ESTIMATE) / 6
- Assuming that the optimistic and pessimistic estimates should be equidistant to the most likely estimate. Positive and negative risks are rarely equal.
- Not accurately identifying all positive and negative risks that can affect a project.
- Intentionally downplaying negative risks, due to political pressure.
- Using too little data to support the estimates used as inputs into the formula.