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."
Compute cluster-aware significance and sequential corrections
Cluster-Randomized Tipping UI Experiment: Power, Sequential Testing, and Multiplicity Context: A creator-level (cluster) randomized experiment evaluat...
Estimate causal effect with interference
A/B Test With Noncompliance and Interference: Causal Effect of Surge Recommendations on Completed Trips Context You ran an A/B test that assigned some...
Choose between A/B and switchback for spillovers
Airport Driver-Queue Algorithm: Experiment Design and Causal Reasoning Background A new driver-queue algorithm is being tested at a single airport wit...
Model preference without ground truth
Problem: Designing an Uplift Modeling and Evaluation Strategy for Event Notifications Without Ground-Truth Labels You need to decide which users shoul...
Define metrics and design experiments for notifications
Analytics/Experimentation Case: "Your friend is attending a local event—join them?" You are evaluating a proposed notification: "Your friend is attend...
Write SQL to compute max-overlap lists
Invented schema and sample data below. Assume 'today' is 2025-09-01 and 'last 7 days' means 2025-08-26 through 2025-09-01 inclusive. Only consider lis...
Brainstorm how to optimize email engagement
Lifecycle Email: Increase Incremental On‑Site Engagement You own lifecycle email for a large consumer app and are tasked with increasing on‑site engag...
Deliver an elevator pitch and impact example
Elevator Pitch + End-to-End Experimentation Case + “Why Meta?” Context You are interviewing for a Data Scientist role during a technical screen. Use c...
Investigate visit–report correlation causality
Causal Diagnosis: Do More Ad Page Visits Cause More Reports? Context You observe a positive correlation between the number of ad page visits and the p...
Implement piecewise linear interpolation for time-to-empty
Time-to-Empty from a Discharge Curve (Piecewise Linear Interpolation) Implement a function time_to_empty(checkpoints, current_soc) that returns the nu...
Determine intersection dimension of two 4D subspaces
Let Y and M be 4-dimensional subspaces of a 7-dimensional vector space X over R. Using dim(Y) + dim(M) = dim(Y + M) + dim(Y ∩ M), determine all possib...
Model overdispersed counts; estimate treatment lift
Weekly posts per creator are overdispersed and zero‑inflated. In a creator‑level randomized test of a nudge: - Control: n_c=40,000 creators, total pos...
Design success and guardrail metrics
You are launching a new recommendation module on a content platform. Design a metrics framework and an experiment plan. A) Define one primary success ...
Design experiment with network and novelty effects
Experiment Design: New Calling Feature with Network Interference and Novelty Effects Context: You are launching a new calling feature on a large socia...
Compute expected payoff of reroll dice game
Repeated Die Rolls with Stopping Rule and Costs You repeatedly roll a fair six-sided die. After each roll you immediately receive a payout equal to th...
Choose metrics for fake-user classifier
Classifying Fake Accounts: Metrics, Capacity, Thresholding, and Validation Context - Population: 10,000,000 daily active users (DAU) - True fake rate ...
Prove source growth is cannibalization, not incremental
Causal Analysis Design: Is Web Growth Incremental or Cannibalization? Background You observe that revenue attributed to creation_source = "web" is hig...
Write SQL for revenue and advertiser analyses
Use the schema below and ANSI SQL. Treat “today” as 2025-09-01. Schema: - active_ads(date DATE, ad_id INT, advertiser_id INT, creation_source VARCHAR,...
Design and power an incentive experiment
Experiment: Timing and Efficacy of Onboarding Benefits Context You operate a two-sided marketplace with supply-side candidates who often complete requ...
Write SQL for cold-complaint diagnostics with LAG/QUALIFY
Using BigQuery/Snowflake-style SQL (CTEs required; use LAG and QUALIFY), answer the tasks below. Assume 'today' is 2025-09-01. Schema and small sample...