An earnest question I've heard from people trying to switch is: what's a good benchmark for testing where you stand in terms of coding skills? How do you calibrate and measure your production-quality coding skills in Scala, C, etc. when you have spent all your life in academia?

I feel Kaggle is sufficient for the exploratory part of data science. But Kaggle's relevance to testing and honing "production quality" code-writing skills is sometimes minimal.

In the larger context of programming and software engineering, scientific programming is fairly easy to code-up (though they are harder to conceptualize and understand mathematically). The coding part of non-CS/non-CE/non-some-parts-of-EE academia is pretty much mostly scientific programming. Yet, production quality code is seldom just scientific programming.