First, you need to pass the 3-hour test. I think they pick three people based on the scores, and the interview is with three interviewers. I was interviewed by the branch head and two librarians.

Panel interview typically 3-4 people from the department that you are interviewing for. They have a set list of questions to ask and will typically take turns. Then they'll let you know how the job works and information about annual raises and other aspects of the job. Star method is very helpful but not necessarily required.