PLEASE DON'T TAKE THE PHONE SCREENING LIGHTLY! I did and got rejected. I was expecting SQL questions and in general talk about my resume but she asked me a question on product sense and I was completely unprepared for it. Creation of Facebook user groups has gone down by 20%, what will you do? sounds simple but I messed it up so badly. I was just blabbering anything in an unstructured way, I sounded so stupid and not even fit for a small company forget Facebook. The recruiter was nice and she did not say anything but I were to hear my own answer, I would reject myself on spot. I regret it so much wish I could have prepared for it. I hope someone sees this and it helps them. The SQL questions were easy and I did answer them correctly- what kind of joins to get only common rows, what the natural sorting order etc.

Design an A/B test to evaluate a new ranking algorithm for the Facebook News Feed. Walk through metric selection (engagement, time-spent, MSI, well-being), unit of randomization given network effects between friends, sample size and power calculations, how you'd detect novelty effects vs. true lift, and how you'd handle a guardrail metric regressing while the primary metric is up.