I applied online. I interviewed at TikTok (San Jose, CA) in Feb 2026
Interview
I had two rounds of interviews. The first one asked about my research project, gave a Leetcode SQL problem, and also asked about social media usage and opinions. The second one again asked about research and some practical questions like what kind of metric would you choose to measure whether the answer provided by AI in the Tiktok app is useful to the users.
A former colleague referred me to the Data Scientist position at TikTok, which kicked off the interview process. The technical screen included a question about designing an A/B test for a ranking model, followed by an SQL challenge related to user sessions. The funny part was that the SQL problem was a twist on one I had been grinding through on PracHub just a few days prior. After some behavioral interviews, I received an offer, but ultimately decided to decline as it didn't align with my goals.
Interview questions [2]
Question 1
Walk me through how you'd design an A/B test for a new ranking model on the For You feed, and how you'd pick guardrail metrics.
Given a sessions table (user_id, session_start, session_end, country), write SQL to find the users whose average session length grew the most week-over-week.
I applied online. I interviewed at TikTok (Londres, Inglaterra)
Interview
one medium level sql test and an open question
Since i'm not familiar with business context(though i actually spent time preparing AB test and causal inference), i didn't get what i should answer.
Interview questions [1]
Question 1
if tiktok shop is going to launch in Netherland, how to evaluate it before AB test