does faster velocity reduce commit quality?

correlation of velocity to good commitsOne assertion I hear, especially from managers, is that when the work volume increases, the commit error rate increases. By commit error, I mean a source code commit that has some form of technical debt, be it an uncovered line/branch, static code violation, duplicated code, tangle or exceeding a complexity metrics threshold.

So I plotted monthly velocity (file commits) on the vertical axis and the corresponding monthly commit success rate on the horizontal axis. For a 2-million line Java over 50 months I plotted a linear regression line on the XY plot.

What were the results? Absolutely no correlation. One the busiest months had the best quality rate and one had the worst.

This jives with my experience. I’ve often seen the busiest teams with the tightest deadlines still deliver debt-free projects. They have a constant focus on their technical debt and strive to commit code with no Eclipse yellow warnings and all green code coverage. On the other hand some teams seem to ignore quality figuring no one seems to care.


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