After a phone screen from the internal recruiter, I also had a phone screen with a senior data scientist. It was fairly straightforward, with the most difficult question being to pick a machine learning algorithm and describe how it works. Then, I had three half-hour interview sessions, and one longer interview session all on the same day in person at the chicago office. The first three mostly just had me discuss machine learning I had done in previous projects at school and work, were fairly conversational and straight forward. My fourth interview was a little trickier, as it contained a couple coding questions and typical "top data science interview questions" you might see on line. Nothing was terribly difficult. It was obvious they just wanted to make sure you know your stuff and would work well with the team.