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The Program Evaluation Review Technique (PERT) method is often used in project management and production analysis. The PERT method is a tool that calculates the expected duration of the project or an individual process. When managing projects, the PERT method usually used in conjunction with the critical path method Critical Path Method (CPM).

The PERT method and the critical path method are fundamentally different in their application area. The critical path method is used to estimate the completion time of the entire project or groups of interrelated tasks, while the PERT method is used to estimate the duration of individual tasks. The very idea of the method is extremely simple, i.e. in order to estimate the time it takes to complete a task or process, one needs to know the optimistic, pessimistic, and most likely estimate of the duration of this task. The PERT formula is:

Picture of « Critical path method”

O – optimistic estimate of the task duration,

M – the most likely estimate of the duration of the task,

P – pessimistic estimate of the problem duration.

Picture of “PERT Chart”

This equation is nothing more than a weighted average, where the most likely estimate of the duration is 4 times greater than the optimistic and pessimistic estimates. This approach prevents too much bias in one direction.