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TikTok·Data Scientist·Technical Phone Screen·Senior

Senior
Jul 2026

Summary

TikTok data scientist interview with a stats-heavy question about comparing creator behavior across cohorts. Pretty technical, felt like they wanted to see if you actually know when to use which test rather than just naming tools.

Questions Asked (1)

Q1

After computing cohort-level posting metrics, how would you determine whether posting patterns differ across cohorts? Walk through the metrics, visualizations, and statistical tests you'd use, and explain what would drive your final conclusion.

A/B Testing & ExperimentationProduct Analytics & Metrics
Author's notes

I started with the visual layer, retention curves overlaid per cohort, average posts per user over time, that kind of thing.

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AI HintsAI Generated

Suggested Approach

Start by defining cohorts and the posting metrics you computed, then outline a layered analysis: descriptive statistics and visualizations to spot patterns, followed by appropriate statistical tests to confirm differences. Conclude by interpreting results in the context of TikTok's product and business goals, considering practical significance and potential confounders.

Pro tip: Emphasize that statistical significance alone isn't enough—quantify effect sizes and relate them to business impact, such as changes in user engagement or content diversity, to show you think like a TikTok data scientist.

1. Define cohorts and metrics

Clarify how cohorts are defined (e.g., by signup date, region, user type) and which posting metrics you computed (e.g., posts per user, posting frequency, content type distribution). Ensure metrics are comparable across cohorts.

2. Explore with descriptive statistics and visualizations

Compute summary statistics (mean, median, variance) per cohort and create visualizations like box plots, bar charts with error bars, or time series to visually inspect differences and trends.

3. Select and run statistical tests

Choose tests based on data type and assumptions: e.g., ANOVA or Kruskal-Wallis for multiple cohorts, t-tests or Mann-Whitney U for pairwise comparisons, chi-square for categorical metrics. Check assumptions and adjust for multiple comparisons.

4. Assess practical significance and confounders

Calculate effect sizes (e.g., Cohen's d, eta-squared) and confidence intervals. Consider potential confounders (e.g., seasonality, platform changes) and whether differences are meaningful for TikTok's product.

5. Synthesize and conclude

Integrate statistical findings with business context to determine if posting patterns truly differ. Recommend next steps, such as deeper dives or experiments, if needed.

Key Points to Mention

  • Cohort definition and metric selection (e.g., posts per user, posting frequency, content type)
  • Descriptive statistics and visualizations (box plots, bar charts, time series)
  • Statistical tests: ANOVA, Kruskal-Wallis, t-tests, chi-square, with assumptions and multiple comparison corrections
  • Effect size measures (Cohen's d, eta-squared) and confidence intervals
  • Confounders and practical significance in TikTok's context
  • Business implications and potential next steps (e.g., A/B tests, deeper analysis)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.