Stabilizing your process takes time. Look for the cause, but don??™t overreact.
Your process may have a lot of variation, and the tendency early on is to shoot the
messenger. If people believe that bad things happen to people when the data are not
what is expected, the people will find ways (devious and nefarious ways) to make
the data acceptable. This is not what you want.
Process Performance Model
A closely related concept to the PPB is the Process Performance Model (PPM). The
PPM describes the relationships among attributes of a process and its work products,
and is used to estimate or predict a critical value that cannot be measured until
later in the project??™s life??”for example, predicting the number of delivered defects
or predicting the total effort. Attributes of a process include productivity, effort,
defects produced, defects detected, and rework. Attributes of a product include size,
stability, defects contained, response time, and mean time between failures. PPMs
are built on historical data and are often built from PPBs.
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