What is PERT and how to calculate the formula?

PERT (Program Evaluation and Review Technique) is a project management method used to estimate task durations considering uncertainty.

The basis of PERT is the calculation of the expected task duration based on three estimates:

• Optimistic time (O) — the minimum possible time to complete the task.
• Most likely time (M) — the most probable time to complete the task.
• Pessimistic time (P) — the maximum possible time to complete the task.

The formula for calculating the expected time (TE) using the PERT method:

TE = (O + 4M + P) / 6

This is a weighted average, where the most likely time has a greater weight.

Example: If the optimistic time is 2 days, the most likely is 5 days, and the pessimistic is 14 days, then the expected time is:

TE = (2 + 4*5 + 14) / 6 = (2 + 20 + 14) / 6 = 36 / 6 = 6 days

PERT helps in planning and managing project schedules, taking into account uncertainty in time estimates.