My laconic question was downvoted. Sorry, I was on my phone, but didn't want to forget about this. I'm sincerely interested in reading the source of this research. Searching for it now, I came across this article:

https://www.microsoft.com/en-us/research/publication/the-spa...

But is this really the one you mean? Even the abstract states that there is no single metric that measures developer performance, which contradicts your claim:

> Developer productivity is about more than an individual’s activity levels or the efficiency of the engineering systems relied on to ship software, and it cannot be measured by a single metric or dimension

So I'm still interested in reading the research you're talking about, and I would appreciate a reference. Thanks!