Data Scientist Interview Questions
Practice 2,964 real Data Scientist interview questions for 2026. Data Scientist interview questions drawn from Meta, Capital One, Amazon, Google, TikTok and similar employers — real questions from actual interviews with detailed solutions — designed to accelerate your interview preparation for product analytics, ML and production data roles. This collection emphasizes the practical skills interviewers test: SQL and data manipulation, experiment design and A/B testing, statistical reasoning, Python coding for data problems, model evaluation and feature engineering, plus machine-learning system tradeoffs and metric design. What’s distinctive about modern data-science loops is the blend of product thinking and reproducible ML: expect hands-on SQL tasks and funnel analysis in screens, deeper experiment-design and causality questions in mid rounds, and coding or modeling challenges plus ML-system discussions in senior loops. Interviewers evaluate problem framing, statistical rigor, and how you communicate decisions to product partners. To prepare, prioritize daily SQL practice (CTEs, window functions), refresh hypothesis-testing and power calculations, rehearse concise metric-driven narratives, and build a few end-to-end model or experiment stories you can explain clearly under time pressure.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Identify trees, lists, and array search costs
Answer all parts concisely and justify time complexities. a) A data model requires each node to have at most two children and a single parent. Name th...
Write SQL filtering, grouping, CASE, UNION tasks
Use the following schema and sample data to answer all parts. Assume standard ANSI SQL and that amounts are DECIMAL. Table: orders +----------+-------...
Select max-discount product per category
You have a catalog of products. For each category, return exactly one product: the one with the largest absolute discount; if multiple products in the...
Write SQL to verify quarterly sales decline
You are given a single dataset for a beverage company and must decide whether Q2 2024 truly declined. Write one standard SQL query that produces a com...
Design Biker metrics and A/B test plan
A delivery marketplace is piloting a new courier mode called "Biker" in dense urban zones to improve efficiency. Assume data access to orders, courier...
Control error under multiple testing
Multiple Testing and Sequential Monitoring with 1 Primary and 12 Secondary Metrics Context You are monitoring an A/B experiment over 4 weekly looks. T...
Diagnose a non-significant experiment outcome
A/B Test Interpretation, Power, and Decision-Making Under Asymmetric Loss Context You ran a two-sample A/B test on a primary mean metric (two-sided t-...
Measure speaker impact without A/B testing
Your company launched an optional smart speaker on 2025-01-10. Adoption is voluntary; 6% of existing app users purchase within 60 days, and you cannot...
Compute power and cost-aware thresholds
You are evaluating a new ACH velocity+shared-device block rule. Assumptions - Volume: 1,000,000 ACH credits/month. - Baseline fraud prevalence: 0.15% ...
Explain motivations, background, and success metrics
Give a concise overview of your background in e‑commerce risk control (30–60 seconds). Then: (1) Why do you want to join our e‑commerce risk team spec...
Run a clean A/B test for autocomplete
Design an online controlled experiment for ML-ranked autocomplete and search satisfaction You are planning an A/B test to measure the impact of an ML-...
Design an experiment for spam filtering impact
Experiment Design: Stricter Spam Filter Impact on Friend Requests Context You run a social app with a friend-request system. A stricter spam filter wi...
Append country tables and rank salaries in USD
You have separate country-level employee tables that must be appended and ranked by salary converted to USD using an exchange rate table. SQL schema a...
Choose regularization norms and model formulations
Regularization and model choice. 1) For linear and logistic regression, write the objective functions with L0, L1, L2, and L-infinity penalties in bot...
Explain motivations, customer ownership, mentoring, and culture fit
1) Why are you leaving your current company? Answer in <90 seconds, avoid negativity, and tie your reason to specific growth you seek (e.g., owning an...
Demonstrate stakeholder communication and influence
Describe a time you influenced a cross-functional decision using data when stakeholders initially disagreed with your recommendation. Include: the dec...
Diagnose a metric drop in search time
Over the last 3 calendar months, the metric 'searching time per user per session' dropped by 35%. A teammate proposes modeling two distributions: T1 =...
Decide whether to launch Group Story
A new Group Story feature may cannibalize regular stories but increase overall engagement. Propose the experiment and decision framework: 1) Identify ...
Detect leakage and evaluate a prediction model
Churn Prediction Model: Leakage, Validation, KPIs, Interpretation, Monitoring Context: You inherit a weekly-scored model that predicts whether a user ...
Design and power an A/B on question mix
Experiment Design: Replacing 10% "Other" Verbal With Grammar in a 15-Min, 19-Question Section You need to test whether replacing the 10% "other" verba...