What? Well, my math review forces me to go read about things I know. And, things I didn’t know, or things I never bothered to connect before.

In statistics, or in all math, independent variables are orthogonal. And, in equations one side of the equal sign is a collection of independent variables are independent, and the variables on the other side of the equation sign are dependent variables. Independent and dependent variables have relationships.

Now, change subjects for a moment. In MS project or in all projects, you have independent tasks and dependent tasks. And, these independent and dependent tasks have relationships.

Statistics was built on simple math. Simple math like the Pythagorean Theorem. You can argue about what is simple, but the Pythagorean Theorem is math BC, aka before calculus.

Distance is one of those simple ideas that gets messy fast, particularly when you collect data and you have many dimensions. The usual approach is to add another dimension to the Pythagorean Theorem. That’s what I was expecting when I read an email sent me out to the *Better Explained* blog, The author of this blog always has another take. I read this month’s post on another subject and went to look for what else I could find. I found a post, “How to Measure Any Distance with the Pythagorean Theorem,” Read it. Yes, the whole thing. There is more relevant content than I’m going to talk about. The author of this post assumes a Euclidean geometry, which around me means my data has achieved normality.

He build up slowly. We’ll just dive in the deep end of the cold pool. You know this stuff like me, or like me, assume you know this stuff.

In this figure, I labeled the independent and dependent variables. This labeling assumed finding z was the goal. If we were trying to find b, then b would be dependent so the labels would be different.

In the software as media model, **a** would be the carrier code, and **b** would be carried content. Which implies a **b** is the unknown situation. The developer doesn’t know that stuff yet. And, without an ethnographer might never know that stuff. Steve Jobs knew typography, the developers of desktop publishing software 1.0 didn’t. But, don’t worry, the developers won the long war with MS Word for Windows, which didn’t permit graphic designers to specify a grid, which could be done in MS Word for DOS. Oh, well.

Those triangles would be handoffs, which is one of those dreaded concepts in Agile. The red triangle would be your technical writer; orange, your training people or marketing. However, you do it, or they do it.

There are more dependent variables in the equation from the underlying source diagram so I drew another diagram to expose those.

The independent variables are shown on a yellow background. The dependent variables are shown on a white background. Notice that the dependent variables are hypotenuses.

In an example of linear regression that I worked through to the bitter end, new independent variables kept being added. And, the correlations kept being reordered. This was similar to the order of factors in a factor analysis which runs from steeper and longer working to flatter and shorter. There was always another factor because the budget would run out before the equation converged with the x-axis.

This particular view of the Pythagorean Theorem gives us a very general tool that has its place throughout product management and project management. Play with it. Enjoy.