Today, I realized **Version 1.4 of Statistical PERT – Normal Edition** for all SPERT example workbooks and templates (task duration, expense, revenue, agile, project portfolios, events).

Here’s what’s new in this release:

- I removed the “Unskewed” probabilities which used the mode instead of the mean. While using the mode would, under some conditions, yield a more accurate probability than using the mean, I found that most people were just confused by the difference between using the mode and using the mean. In most cases, using the PERT mean will give accurate results, so I decided to remove the confusion by removing the columns devoted to “Unskewed” probabilities.
- There is a new pie chart and associated cells which lets estimators create confidence intervals for any selected confidence level. You can specify a confidence level and the confidence interval is determined for you, or, optionally, you can give a confidence interval and the confidence level is calculated for you.
- There is a new pie chart showing what uncertainty looks like with respect to how likely is the Most Likely outcome. One of Statistical PERT’s unique attributes is that it allows estimators to use subjective judgment (private knowledge, gut instinct, emotions, intuition) to rationally adjust the SPERT estimates. Many people don’t know how to choose a subjective judgment, though. This new pie chart shows what each subjective choice looks like if the only three outcomes were the minimum, most likely and maximum point-estimates. Interestingly, there was a PMI Global Congress presentation that talked about visually making risk-based choices.
- I standardized the SPERT example workbooks and templates so future changes can be easily made across all the different SPERT example workbooks and templates. So, instead of the task duration’s template having headings like Optimistic, Most Likely and Pessimistic (where the order would be reversed for the Revenue template), now all templates use Minimum, Most Likely and Maximum as the headings for the three-point estimate columns.
- Each SPERT file now has a Welcome! tab that introduces Statistical PERT to the downloader, and it has a link to a Quick Start guide that can help to quickly learn how to use any SPERT download.
- I made a number of other tweaks, too, of a minor nature. SPERT, for example, is now a federally registered trademark.

If you haven’t already done so, I encourage you to download your favorite SPERT example workbook or template!