PMP Formula: Standard Deviation of the Activity

PMP Formula Standard Deviation of The Activity (SD)

Standard deviation (SD) is a statistical concept that gives a measure of the 'spread' of the values of a random variable around the mean of a distribution. It shows how much variation there is from the average or the mean value. The more the variation, the more the uncertainty or risk in the process. By calculating the PERT estimate (mean) and standard deviation of the project duration estimate, we can calculate the probability of completing the project within a given duration.

Formula Definition
SD Standard Deviation of the Activity
  • = (P - O) ÷ 6

  • O = Optimistic Estimate

  • P = Pessimistic Estimate

  • A low value of SD shows that the data points are close to mean or average and a high value of SD shows that data points are spread over a large range.
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