In the Pert,
what happens to the probability of project completion when the variability goes up or down?
Expert Answer
The probability of project completion is computed using z value table and calculating z value as below:
https://d2vlcm61l7u1fs.cloudfront.net/media%2F29a%2F29a33f80-ea0b-41f4-b685-09777dd01573%2FphpAyzTK4.png
Hence, when the standard deviation goes up, the z value will decrease and so the probability of project completion on specified time will decrease.
Similarly, when standard deviation goes down, z value will increase and thus the probability of project completion on specified time will increase.