How to Prepare for a Google Data Scientist Interview (2026)

Google's data scientist interview process has stayed relatively stable over the past few years. There are some quirks worth knowing about before you start studying.

The interview structure

The process typically has 4-5 rounds:

1. Recruiter phone screen (30 min) — Background questions, role fit, timeline expectations. Nothing technical.
2. Technical phone screen (45 min) — Usually a live SQL query plus a statistics or probability question. Sometimes a product metrics question instead of stats.
3. Onsite round 1: Coding (45 min) — Python or R. Expect data manipulation, not LeetCode-hard algorithms. Pandas questions come up often.
4. Onsite round 2: Product/Analytics (45 min) — Metrics definition, experiment design, A/B testing. "How would you measure the success of X?" is the bread and butter.
5. Onsite round 3: ML/Modeling (45 min) — Model selection, feature engineering, bias-variance tradeoff. Sometimes a case study where you walk through building a model end to end.

Some candidates get a 4th onsite round. This is usually behavioral or a repeat of whatever area the team felt was borderline.

What to study, ranked by importance

SQL is non-negotiable. The phone screen SQL question will likely involve window functions, self-joins, or date manipulation. If you can write a running average and a cohort retention query without looking anything up, you are in decent shape.

Product metrics come up in every loop. You need to be able to define success metrics for a product, design an experiment to test a change, and interpret results. Practice with real Google products: Search, YouTube, Maps, Gmail.

Statistics shows up more than people expect. Hypothesis testing, confidence intervals, p-values, Bayesian reasoning. The questions are not textbook — they are applied. "You ran an A/B test and the p-value is 0.06. What do you do?"

ML is tested but less heavily than the others unless the role is specifically ML-focused. Know the basics: linear/logistic regression, decision trees, overfitting, regularization, evaluation metrics.

Coding at Google DS interviews is closer to data manipulation than software engineering. Think pandas, not dynamic programming.

Common mistakes

People over-prepare for LeetCode and under-prepare for product sense. Google's DS interview is not an SWE interview. The coding is lighter, but the product and metrics rounds trip up candidates who only practiced algorithms.

Another common mistake: giving vague answers in the product round. "We could look at engagement" is not enough. You need specific metrics, how you would measure them, what the experiment design looks like, and how you would handle edge cases in the data.

Relevant practice on PracHub

PracHub has 38 analytics and experimentation questions from Google, 36 ML questions, 32 statistics questions, and 152 coding questions. You can filter by Google + Data Scientist to see questions reported from actual interviews. The SQL questions from Google tend to be more complex than average — window functions and CTEs show up frequently.

Timeline

Most candidates spend 4-8 weeks preparing. If your SQL and stats are rusty, budget more time. If you are already working in analytics, you can probably focus on product sense and mock interviews.

The whole process from recruiter screen to offer typically takes 6-8 weeks. Google moves slowly. Do not read anything into long gaps between rounds.