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.

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"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."
Design and power an A/B test
Email Targeting Model Experiment Design You plan to launch a targeting model via email where: - Treatment: users above a score threshold receive an em...
Derive expectation for two consecutive heads
Waiting Time Until First HH (Two Consecutive Heads) Setup Let T be the number of coin flips required until the pattern HH (two consecutive heads) appe...
Decide best email variant using stratified A/B analysis
Stratified A/B Test Across Two Strata (Week/Location) You ran an email A/B test across two strata defined by week/location. Each user receives at most...
Design a restaurant recommender under constraints
Design a Restaurant Recommendation System (Food Delivery App) Context - Goal: Return the top-20 restaurant recommendations within 5 miles in under 100...
Solve drunk-passenger probability and simulate outcome
Lost Boarding Pass Puzzle: Last Passenger's Seat Context: Technical screen for a Data Scientist (Statistics & Math). Setup - There are n passengers la...
Resolve conflict with measurable outcome
Behavioral: Conflict With a Teammate or Stakeholder (Data Scientist — Technical Screen) Provide a specific, first-person example. Use a clear structur...
Design a hierarchical MF delinquency forecasting system
Forecasting 90+ Day Delinquency Rates for Multifamily Loans: Hierarchical, Leakage-Safe System Design Context You need to forecast 90+ day delinquency...
Compute optimal stopping in a die-rolling game
Optimal stopping with a fair die (3-roll horizon) You observe outcomes of fair six-sided die rolls (faces 1–6) and may stop after any roll to take the...
Evaluate and monitor a credit risk model
Credit-Risk PD Model: Evaluation Priorities and End-to-End Plan Context: You are deploying a consumer credit probability-of-default (PD) model for 12-...
Optimize red-ball draw probability, prove optimality
Two-Box Ball Allocation to Maximize Probability of Drawing Red Setup - You have 2 boxes and two colors of balls. - In the 100/100 case: 100 red and 10...
Evaluate shopping tab pre- and post-launch
Instagram Shopping Tab — Measuring Off‑App Purchases, Opportunity Sizing, and Launch Readout Context Instagram is planning a new Shopping tab. Users o...
Implement R² and Compare PCA With/Without Scaling
NumPy-only implementation: R² and PCA (Data Scientist take-home) Implement from scratch using only NumPy (no scikit-learn). Use float64 throughout and...
Forecast response-rate trends with backtesting
Forecasting Response Rate by Job Category and Week Context You are given weekly marketplace data with invitations and responses by job_category and re...
Train and evaluate logistic model with regularization
Binary Classification with Logistic Regression and Regularization Data - Two CSVs: a training set x and a test set x_test. - Each has 7 columns: - C...
Translate goals into robust product metrics
Analytics & Experimentation: Metric Design and Validation Context You are a Data Scientist working on analytics and experimentation. You are given bus...
Handle disengaged interviewer or biased manager
Behavioral Prompt: Handling a Pre-Decided Stakeholder in a Technical Screen Context: Role = Data Scientist; Round = Technical Screen; Category = Behav...
Calculate A/B sample size, CI, decision rules
A/B Test Design and Analysis: Signup Funnel You are designing and analyzing a two-arm A/B test for a signup funnel. Assume 1:1 traffic split and indep...
Diagnose and reduce cold-food refund costs
Case: Reducing Cost of Cold-Food Refunds While Preserving Trust Context DoorDash currently issues 100% refunds for all "cold-food" complaints, which d...
Analyze A/B test with rigorous diagnostics
A/B Test Analysis Live Walkthrough (Python) Context You are given a user-level randomized experiment dataset experiment.csv with columns: - user_id - ...
Describe resolving revenue–UX metric conflict
Behavioral: Leading a High-Stakes Revenue vs. UX Trade-off Context: You led a decision where ads revenue goals conflicted with user-experience metrics...