I'm mostly looking for people who want to learn about engineering with largeish datasets (~100gb/day for us), and have some of the prerequisite skills. Our codebase is mostly in Spark/Scala and uses functional programming idioms, so I'm looking for people who either know or want to learn how to use those. I'm also specifically trying to filter out people who mostly want a stats-heavy, machine learning heavy job, since that's not what we do.

An engineer who wants to learn data science is a great fit for us, an academic who wants to write R all day is not (though an academic who wants to learn engineering/functional programming is fine!)

Beyond that, I ask some questions about projects they've worked on, and in particular, how their approach would change if assumptions were different. Here I'm looking for the ability to reason backwards from a business goal, as opposed to somewhat blindly applying statistical techniques.

If they do well on these, we send the take-home exam. As previously noted, this is specifically designed to require relatively little knowledge but heavily test analysis skills, and lightly test programming skills. It's almost impossible to complete this exam without using Google effectively, so that's another thing I'm testing.