I applied through other source. The process took 2 weeks. I interviewed at TikTok in Sept 2025
Interview
Code signal screen with SQL. 1st Round was behavioral and whiteboard problem solving, discussed fraud detection with both image hashing and logistical regression. Focused on data set imbalance and methods for over coming problems related to imbalanced data smote and why these are important.
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 (London, England)
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