Don't conflate the inability to measure productivity with the conclusion that for this one issue the differences can't be that large. That's like saying, "just

Don't conflate the inability to measure productivity with the conclusion that for this one issue the differences can't be that large. That's like saying, "just because we can't measure distance or velocity, rockets and cars probably are similar speeds, or it depends on the driver's personality." It's empirically unsolved how productive an engineer even is, therefore all other discussions are 100% subjective. We don't know if there's an effect, because we have no way at all to measure it without costs so staggeringly large no one will ever try. We'd need similar engineers, doing all the same practices, with the same stories, and just one difference. But then the engineers would need to have been selected to be similar skill and speed previously, which would require doing other projects with all fixed practices and languages to measure developer skill relative to peers. This also doesn't take into account team cooperation and morale, creative thinking around problem solving, etc. It's a bummer, but without some breakthrough in AI research allowing developers to be measured based on the code they write, it's seeming more and more like an unsolvable problem.