Ask HN: Research on software development productivity with valid metrics?

OP here. I just realized that it may seem like I'm trying to drive traffic to the post on StackExchange. I was more trying to get some discussion going here as well and see what people might think, as I suspect many people have an opinion on that around HN. I didn't want to duplicate the question, though, and wanted a single point of reference.

But obviously I'm looking forward to comments and thoughts from people who may not be able or wouldn't want to answer on SE.

Sorry if that intent wasn't clear.