After a screening interview with HR and the group leader, the real interview was a 4-5 hour single day meeting on location (pre-covid). Each ~30 min period was dedicated to two group engineers who would be your colleagues. For the data science position it was a nice mix of data and software engineers as well as some discipline leads. There were some difficult technical questions but nothing out of the ordinary. I always thought that interviewers approach these questions like an exam, but in reality it's just a fit screen: if you can't solve these kinds of questions, *you* don't want to be working here either. The focus was on fit, and the most relevant aspect wasn't necessarily technical rigor but appropriateness for the projects. They wanted to know what your threshold was for seeking help, making sure you don't spin your wheels but try to solve it and fail fast.