Meta·Data Scientist·Technical Phone Screen
Apr 2026
Meta DS interview that leaned heavily on statistics fundamentals, more so than I expected. The whole thing revolved around a single scenario about comment counts per user, and they kept drilling deeper from every angle. Left feeling like I probably over-explained some parts and under-explained others.
- Given daily comment counts per active user, define and compute the mean, median, and 95th percentile for a single day. Write out explicit formulas, including how you derive P95 from a sorted empirical distribution.
- Explain the Central Limit Theorem and why the sampling distribution of the sample mean tends toward normality. What conditions are required for it to hold?
- If you draw 200 independent simple random samples of size n from the same day's user comment data, what value of n is sufficient for the sample mean to be approximately normal? And how does the variance of the sampling distribution change as n grows?
- How do plots of the daily mean, median, and P95 each behave as sample size n increases, and what explains the pattern?
- If comments per user increased week-over-week, give at least three plausible statistical or product explanations and describe how you would test each one.
“Felt solid on mean and median but stumbled a bit articulating P95 from an empirical distribution.” The rest of the author's notes on Data Scientist interview at Meta, Technical Phone Screen round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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