So How Do You Use a PPB with Your Projects?
New projects could use the example PPB for estimating their effort based on estimates
of the number of requirements, number of interfaces, number of design
pages, and so on. The range of values (upper, mean, and lower) allows the estimators
to determine the most likely, worst case, and best case estimates of not only
productivity, but also the staffi ng levels that are needed.
We have personally witnessed the positive change in organizations when they
have PPBs that people believe. The estimation and planning process becomes
much more of a professional activity and less emotional. Project managers armed
with PPBs based on historical process performance are less likely to fall victim to
unfounded pressure to lower estimates and reduce schedules.
260 n Interpreting the CMMI
After planning, the PPB can also be used to monitor and control the project??™s
work by comparing the actual number of hours to perform the work against
expected range of values for the PPB element. Remember, if the actual number of
hours is outside the expected range, it is only meaningful if your process is already
stable.
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