On March 10, 2019, I officially released the public version of Statistical PERT Normal Edition. This is a terrific enhancement upgrade to Statistical PERT because Version 3 adds new and enhanced data visualization features that help you see the uncertainty you’re modeling.
New in Version 3:
- Row-level Sparklines that show the shape of the implied bell-curve, based upon your 3-point estimate and subjective judgment about the most likely outcome
- New, tri-colored combo charts which show the bell-curve for the aggregate of all the uncertainties you’ve modeled (in the 1-point entry, 3-point entry, and Mixed entry worksheets)
- Three, side-by-side scenario comparisons on the Agile Forecast tab, to make it easier to do sensitivity analysis when choosing different input variables
Row-level Sparklines are useful because they visually show whether the bell-curve is flat (lots of uncertainty), narrow (not much uncertainty), or shaped familiarly (moderate uncertainty). They also indicate whether your 3-point estimate implies skewing either to the left or to the right. If the peak of the Sparkline bell-curve is centered, there is no skewing. If the peak is shifted to the left, then your uncertainty is skewed to the right, and vice versa. By showing the uncertainty in a Sparkline, you can immediately recognize what kind of uncertainty you’ve modeled, without looking at the actual input data you entered and deciphering mentally.
The tri-colored combo charts is a HUGE enhancement to Statistical PERT. You won’t realize how useful these are until you start to play with them. Their greatest value is they visually show the kind of uncertainty you’re estimating, which is very helpful when presenting or negotiating with stakeholders. Imagine showing your project sponsor (who is under-funding your project) a tri-colored combo chart that has more than 50% of the area under the curve in the color red. You say to your sponsor, “The area under the curve shows the likelihood your project will fail to meet its goal, given the project constraints we have to work with.” And then you explain to your sponsor how you arrived at this conclusion.
The tri-colored combo chart is a combination of a line chart and a bar chart. The colored area under the curve is actually 100 bars that touch each other. The line that touches the peak of each bar chart smooths the appearance of the normal curve. This whole combo chart is configurable — change the bar sizes, colors, much more.
To create the tri-colored bar chart, you’ll notice there are a lot of hidden columns to the right of the main worksheet display. Feel free to unhide these hidden columns and explore how the tri-colored bar chart’s data is created.
This summer, I’ll be working to enhance Statistical PERT Beta Edition to give it the same data visualization upgrade as what the Normal Edition now has. I hope to release Version 2 of the Beta Edition by the end of summer 2019.
I’m working with Pluralsight to release a brand-new course to replace my 2015 course that first introduced Statistical PERT to the world. Statistical PERT has changed a LOT over the last four years, so it’s a great time to replace my 2015 course, Easily Estimate Projects Using Statistics and Excel with my new course, Easily Estimate Projects and Products. This new course will show product owners working in an agile environment how to use Statistical PERT to forecast how many iterations (sprints) it will take to complete a given amount of work off the product backlog. Statistical PERT is a great, easy way for product owners to create feature forecasts.
Look for other, smaller enhancements to Statistical PERT Normal Edition later 2019 and 2020!