I applied through an employee referral and the process took 2 weeks.
The recruiter contacted me the day after my resume was internally referred. Set up a call a couple of days later for a short chat (15 mins) about the nature of the job, my general qualifications and backgrounds, and continued interest in the position. I was immediately notified I'd be moved to the next interview, a 45 minute phone interview with the head of the team. The recruiter was very informative about the subject of the call (statistics, statistical methods/concepts) and background of the interviewer. Interview went well.
Fifteen minutes after that interview concluded, the recruiter called me, asked me how I felt it went, and informed me I'd be moving toward a second (45-minute) phone interview. The call was scheduled for the following week and again, I was informed on the subject of the interview (advanced stats, probability, and live syntax for data management) as well as the background of the interviewer (quantitative engineer). The call went well, though I did stumble a little bit over the syntax (I'd just taught myself over the weekend), but not because it was difficult.
I did take my time to prepare and I was right. It is a difficult test. I did use apps like ‘the impossible interview’ and ‘the aptitude interview’ from iTunes app store to prepare. They were a help.
A week later I was informed my interviews went well, and I did make it to the next round.