Robert Stoddard has provided an excellent resource to help plan process performance models See here  Reproduced Below is an extract one of the key slides.

• Statistical, probabilistic or simulation in nature
• Predict interim and/or final project outcomes
• Use controllable factors tied to sub-processes to conduct the prediction
• Model the variation of factors and understand the predicted range or variation of the outcomes
• Enable “what-if” analysis for project planning, dynamic re-planning and problem resolution during project execution
• Connect “upstream” activity with “downstream” activity
• Enable projects to achieve mid-course corrections to ensure project success