An advantage of using probabilistic time estimates is the ability to predict the probability of project completion dates. We learned how to calculate the expected time for each activity with the three time estimates provided. Now we need to calculate the variance for each activity. The variance of the beta probability distribution for each activity is
where p = pessimistic activity time estimate
o = optimistic activity time estimate
EXAMPLE 16.6 Calculating the Variance of Activities
Calculate the variance of each activity in the Cables By Us project. Then calculate the variance associated with each connected pathway through the project.
• Before You Begin: The variance is calculated using the formula
Using activity A to illustrate the formula, the variance is 0.44:
Using the variance for each activity, calculate ...