Mercer did their hiring for this position through the Randstad agency. The initial Randstad phone interview was excellent. The interviewer did not read from a script but asked questions to get at the meat of my experience and what I was looking for in a position. (no phony "tell me of a time that you....")
After the phone interview I was sent a link to take an on line test (the test is from Mercer, not from the agency) The test was personality (similar to an MBTI test) math (lots of percentage and ratios) and a call center simulation that I found enjoyable.
Two days after completing the on line test I found another job so will not be accepting the request for an interview. However I was impressed by the Mercer test and am betting they hire quality staff and I would have liked working there.