Haven't had yet the interview (this is my first time looking for a job in the US) but can tell you that after they select your Resume, they send you a case for you to solve in app a week. The case I receive was about identifying problems and finding solutions for reducing the therapy drop out rate in an hypothetical situation in a public hospital (diabetes patients). I was very fun but took my a while. I had to do data analysis but was relatively simple (obtain p-values).

ideas42 has an extremely stretched-out hiring timeline, which is disrespectful to applicants. You cannot expect people to wait around for 4 months for a hiring decision. Also, if you're going to waitlist applicants BEFORE interviewing them, at least provide some feedback on the extensive case study required in stage two. What a frustrating and non-transparent process.

One-hour long Skype session focusing on how to incorporate behavioral economics in life situations and general personal questions. Chatted somewhat informally over the course of an hour. Didn't ask anything requiring a calculator.