Today marks the release of two editions of Statistical PERT®: the Normal Edition and the Beta Edition. The Normal Edition is the original Statistical PERT that uses Excel’s two normal distribution functions, NORM.DIST and NORM.INV. The Beta Edition uses Excel’s two beta distribution functions, BETA.DIST and BETA.INV.
The Normal Edition of Statistical PERT is a full version upgrade to Version 2. The Beta Edition is still a development build, so it is Version 0.6. The 1.0 release of the Beta Edition will occur later in 1Q 2017.
Both the Normal Edition and Beta Edition look very similar, and both follow the same easy approach to probabilistic estimation:
- Create a three-point estimate (minimum, most likely, maximum)
- Render a subjective judgment about how likely the most likely outcome really is
- Choose a probabilistic planning estimate or make a risk-based forecast
The new releases of both the Normal Edition and Beta Edition offer estimators the option to use one-point estimates and heuristics to calculate the minimum and maximum point-estimates. Estimators can still specify their own minimum and maximum point-estimates, too, if they choose.
This latest release of SPERT-Beta is a Version 1 release candidate, meaning that I don’t expect to add any new features to the current development build.
Try both editions of Statistical PERT!