It's worth pointing out that this blog post was published three years before Accelerate, by Forsgren, Humble, and Kim. That book demonstrates what you can do just with surveys. It's not about software engineering per se - it's got a devops focus - but the overlap is significant.

As far as I'm concerned that book significantly changed the game, not only because of the findings, but because it showed that hard results are possible in this arena. The downside is that you need enough data to make the maths work, and that precludes applying the techniques to internal studies in most organisations. There's just too much noise.