One of the most important lessons I've learned in my career is that if a common problem has existed for a long time, a simple solution has probably been hiding in plain sight for a long time somewhere you haven't thought to look. I don't know anything about productivity research, but the fundamentals of defect density were figured out decades ago [1].
> (a) there’s no difference between test-first and test-after but (b) interleaving short bursts of coding and testing is more effective than working in longer iterations
I'm glad you quoted this study because it's a perfect example of a conclusion that should have been the starting point of a more interesting experiment. Interleaving code and test is known to be the most impactful factor. TDD and TRL don't differ in any of the ways that account for the vast majority of defects. Therefore of course the difference should be small, and of course shorter iterations should be better.
> (a) there’s no difference between test-first and test-after but (b) interleaving short bursts of coding and testing is more effective than working in longer iterations
I'm glad you quoted this study because it's a perfect example of a conclusion that should have been the starting point of a more interesting experiment. Interleaving code and test is known to be the most impactful factor. TDD and TRL don't differ in any of the ways that account for the vast majority of defects. Therefore of course the difference should be small, and of course shorter iterations should be better.
[1] https://www.slideshare.net/AnnMarieNeufelder/the-top-ten-thi...