hey guys,
so turns out you're right, the panels consists of 4 interviewers. I searched google to find out more information about waterloo's interview and I found this article, which I think is very helpful:
http://futurepillpusher.com/index.php?topic=9.0
Also, my friend did the waterloo interview last year (but got rejected) so I asked her about it and supposedly they only had 3 interviewers last year consisting of pharmacists and students and she said the test was a basic journal article (I think her's was psychology based) that you need to summmarize the results and discussion of. She also said that you should be confident and that they will question you back on your answers.
I've decided to reject my interview offer so hopefully one of the sdn members who got rejected will have an interview now
and I wish you guys all the best on your interview. Hope my information was helpful in some way