Program Evaluation and Review Technique (PERT)

Standard Deviation

the square root of the sum of the variances of the individual activities.

Mean project duration

a straightforward sum of critical path activity means

When is PERT used

projects where there is insufficient historical knowledge for estimating project activity duration's

Standard Deviation

provides an indication of the uncertainty associated with the mean estimate of activity duration.

PERT Recognizes what

the probabilistic nature of activity duration's as opposed to the deterministic assumptions that CPM incorporates.