It was a 75-minute interview. The conversation was loosely framed around a set of questions that the interviewer chose. It looked like he had to pick 2-3 out of 5-10 questions per category, so it wasn't as bad as when they're forced to ask really specific questions. The questions were about how I work on my own, in groups, what challenges I faced and how I faced them, and a few scientific questions. The interviewer was easy to talk to, and before I knew it the 75 minutes were over. It felt like having a regular conversation.