The discussion in Chapter 8 focused on asking task leaders how often they could expect, in the worst case, that their task would overrun their "most of the time" estimates. In developing the details of risk analysis, task leaders are asked to consider why their task could overrun. Asking why the task could overrun yields better task time overrun estimates and provides a basis for planning mitigation strategies to store in the task's notes and to use when an overrun seems to be developing during a task's execution. There is always more than one reason that a task might overrun. Each task leader is asked to list all the significant potential overrun causes and to analyze each one separately. The cause that produces the greatest contribution to the risk factor (D x Y) yields the contribution that is provided by the task leader in the determining of the risk factor.
In Chapter 8, the discussion of the risk factor was focused on critical path tasks. However, noncritical path tasks can sometimes cause a greater overrun impact than their parallel critical path tasks. The task leader of a noncritical path task must determine his or her tasks D and Y just as the critical path task leaders do. If the noncritical path has a D that is greater than the slack between it and the next critical path task, its potential for contributing to project overrun must be examined.
The project manager will ask each task leader to determine the worst case task time overrun duration (D) and the likelihood that the task will overrun (Y) to provide data for risk analysis. In the preceding chapter, this was discussed in general terms so that the basic concept could be explained. In practice, a project manager will ask each team member to go beyond a general analysis and look at each significant factor that could cause the task leader's task to overrun. For one task, problem sources such as uncertainty about a team member's availability, technical complications, and late delivery of ordered parts could each cause a delay. The project manager then asks each task leader to separately calculate the potential risk factor contribution for each possible problem source and to report the largest as his or her task's risk contribution. The project manager leads the team in a review of all their contributions from critical path tasks to determine good risk factor insertion points along the critical path. In addition, the project manager leads the team to consider possible project delays from tasks not on the critical path.
Although the work is detailed and may seem a little tedious, it is very important. The magnitude of the required effort is manageable because each team member only has to do a small part of it.