I applied online and got an on-site interview offer after more or less three weeks. They sent me a temporary American Express credit card for my travel expenses to the New York office. We took an hour-long test which was much like a written case study analysis and quantitative problem solving. And then we were divided into several groups for the case study discussion led by McKinsey consultant. Most of the candidates were PhDs from Ivy league schools and some of them were MDs or medical students at the ivy.