Be prepared on your past experiences. They will come out of the blue to judge your confidence and ask questions on statistics in detail and you might have not imagined will come in front of you.

Had 4 rounds of interview - first was telephonic hr round where they just asked about the current job and profile. Second one was technical video interview with the potential super boss - he was very polite and immediately made me feel at ease. Asked me some questions on previous work experience. He sent over a powerpoint deck with data tables (without analysis, summary, reccos) at the end of the interview and asked me to analyse, create a summary, reccos and a story, and present to him in a week's time. The 3rd round was the presentation round and he grilled me on the presentation (like a client would). I enjoyed the process - the questions asked were very valid and only a good researcher with experience could answer them.