Meta Data Science interview questions

I was first contacted by a sourcer for a different position, but the recruiter that she connected me to never replied my email. A few months passed, I received an offer from another company so I thought I'd check in with the recruiter again. He emailed back, but ultimately the position he was recruiting for wasn't a good fit. He passed me to a second recruiter, who's super efficient in terms of both scheduling and getting back to me with the results. It took him literally less than 24 hours from the beginning of my interview to get me a verbal offer. Super impressive. For the onsite, there were 5 back-to-back 30-min interviews. It was quite intense, and a lot of talking. They should've fit a 5 min break here and there, but oh well. There's a few algorithm questions, stats, design, research background, etc.

My resume was entered into the system by a friend who currently works there, but after a week and no contact, I applied online to a Data Scientist position. Data scientists at Facebook have a totally separate hiring process from software engineers. You have an initial phone screen by a data scientist which will focus on your 'analytical ability.' For those of you who (like me) have no idea what that means, it means a tiny bit of coding/scripting in a language of your choice while you work a reasonable, made-up data science scenario. They'll give you pretend access to a pretend database of information, have you write a few queries, give you fake data for your output, and have you debug plausible scenarios for that fake data. I received word rather quickly (two days later) that I passed the phone screen and would be invited to Mountain View for a day of interviews. I scheduled those interviews for 3 weeks down the line. Interviews at Mountain View are grueling, not because of their technical difficulty, but rather because of the interview setup. I was interviewed in a tiny closed cubicle no more than 8 feet x 8 feet; room for two one-seater couches and a tiny table. The wall was a whiteboard. There were 5 back to back 30 minute interviews, and while the interviewers were apparently supposed to ask if I needed water or a bathroom break, they often forgot to do so. The next interviewer was waiting right outside when the last interview ended. After we covered all of the technical content (about which I signed an NDA, so I unfortunately will not share the details of that), I had about 120 seconds to quiz my interviewer about what data science is like at Facebook. I may have earned brownie points with one on-site interviewer for stopping him when he started asking me the same question that I had had during my phone screen. He thanked me and changed to a new problem. I studied for the Data Scientist interviews by: a) coding in python (which I do for my job; they were happy to let me code in python for the on-site interviews) b) reviewing Stanford's online statistics 101 class c) doing a few 'hat trick' type probability puzzles I was well prepared for their interview questions. I heard back from my recruiter 1 week after on-site interviews and received a generous offer with a fungible 2-week acceptance deadline.