Statistical PERT® Normal Edition, Version 5.1.2, released January 8, 2024, is a very minor change to update the date data values to 2024-2025. Version 5.1 made it easier to legally indicate in the worksheet footers when this spreadsheet is modified by another author (who updated the Change Log worksheet correctly). Version 5.0.3 added optional call-outs on the Burn-up Chart worksheet, to make it easier for stakeholders to read the probabilistic delivery dates. Version 5.0.2 added a new lookup so the user can indicate whether they are a Frequentist or a Bayesian statistical modeler (or whether they don’t know or care). Version 5.0.1 added some very minor formatting improvements and a new “WIP Only” chart on the CFD Charts worksheet. Version 5 is a major update to the Normal Edition. There are two new features of Version 5. The first major feature is the SPERT® Normal Scheduler worksheet. The Scheduler worksheet lets users create a probabilistic schedule by estimating the time duration of a project’s critical path. The second major feature is the SPERT® Normal – CFD Charts worksheet which lets users create a cumulative flow diagram (CFD) that visualizes a team’s workflow. Version 5 also has improved bell-curve graphics with double the number of sampled data points. Statistical PERT Normal Edition uses Excel’s two normal distribution functions, NORM.DIST and NORM.INV to create probabilistic estimates.

Statistical PERT® Beta Edition, Version 3.3.2, released January 12, 2024, is a very minor change to update the date data values to 2024-2025. Version 3.3. made it easier to legally indicate in the worksheet footers when this spreadsheet is modified by another author (who updated the Change Log worksheet correctly). Version 3.2 added double the number of random data points used to create the tri-colored, bell-shaped charts. These charts now have a sharper, smoother appearance. Other minor tweaks are also included to improve consistency and appearance. Version 3 has two new features and one enhanced feature.  The first new feature is a Monte Carlo simulation worksheet for modeling a single, random variable using the beta distribution.  Another new feature is SPERT® Beta Scheduler, which allows for easy, probabilistic scheduling of plan-driven projects.  Finally, the Agile Forecast worksheet is enhanced to allow for a side-by-side comparison of up to three scenarios, making it easier to do what-if analysis.  Statistical PERT Beta Edition uses Excel’s two beta distribution functions, BETA.DIST and BETA.INV to create probabilistic estimates, plus the normal distribution functions, NORM.DIST and NORM.INV, to calculate probabilities assuming the Central Limit Theorem for summary rows.

Statistical PERT® Lognormal Edition, Version 2.0.1, released January 12, 2024, is a slight update to Version 2.0, an upgrade that adds the SPERT Scheduler worksheet. The SPERT Scheduler (which is also available in both the Normal and Beta Editions of Statistical PERT) uses the lognormal distribution to model a project’s critical path uncertainty.  Version 1.0, released January, 2022, is a brand new edition of Statistical PERT. This edition uses Excel’s two lognormal distribution functions, LOGNORM.DIST and LOGNORM.INV, to model uncertainty using the lognormal probability distribution. The lognormal distribution has several modeling advantages: one, it requires only a single point-estimate for the uncertainty (either the most likely outcome which is the mode, or the mean which is the arithmetic average); two, it models uncertainty only using positive numbers; three, it can easily represent uncertainties with a long, right-side tail (which is a common occurrence in project management). Statistical PERT Lognormal Edition also uses Excel’s natural log function LN(), to interact with the other lognormal functions.

Statistical PERT® Bootstrap Edition, Version 1.1.5, released January 13, 2024, is a very minor change to update the example workbook data to reflect 2024-2025 dates. Version 1.1 added explanatory labels to the BootstrapData worksheet, and made it easier to legally indicate in the worksheet footers when this spreadsheet is modified by another author (who updated the Change Log worksheet correctly). The Bootstrap Edition uses statistical bootstrapping to simulate what might get done in the future based upon what has actually been done in the past. This edition of SPERT is useful for agile team forecasting (both Scrum and Kanban teams) who have historical records of what their team has accomplished over at least 6 or 8 iterations. Bootstrapping will simulate future iterations by randomly selecting values from the team’s historical record. Read more about statistical bootstrapping here.

SPECIAL RELEASE for smartphone users – SPERT® Mobile!  Download this special version of Statistical PERT Normal Edition that makes it easy to create probabilistic estimates right on your iPhone or Android smartphone.  You must have Excel Mobile installed on your device to use Statistical PERT.  Excel Mobile is a free download on iTunes and Google Play.

Are you using an iPhone, but don’t have the free Microsoft Excel app for iPhone?  Download it from Microsoft now.

Are you using an Android smartphone, but don’t have Excel installed?  Download it from Google Play now.