I had three interviews overall. The first interview was a 15 minute phone screening interview that went well. The second interview was 2.5 hours long and included a 45 minute long skills test as well as interviews with two different groups of people. The first two interviews were very casual and the people doing the interviews did not seem to have much experience in giving interviews. The third interview was a presentation and interview with the leader of the department I was applying for. It was much more formal.