I was contacted through a (friend of a friend) employee referral. A non-technical phone call was scheduled a week later with a "technical sourcer" employee. I was asked about my research background on that call. A week after, I was scheduled for a technical phone interview with a Data Scientist. The technical phone interviewer was pleasant and experienced. I got the impression that some of the scenarios I was asked to address were at the cutting edge of what Uber was working on at the time. The questions were thought provoking and I enjoyed our conversation. The way the referral process went, I did not have much time to prepare for the interview. In hindsight, I would have spent more preparation time thinking about their business model and quantitative approaches to optimizing the company's services.