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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"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."
Design navigation-safety simulation parameters and experiments
You must design a simulation-based evaluation for navigation safety of an autonomous agent. Be specific: a) Enumerate scene parameters to vary and jus...
Handle unresponsive stakeholders and align metrics
You have 45 minutes, two interviewers are minimally responsive, and the problem statement is vague. Walk through how you will proactively drive clarit...
Design analysis to validate reported decline
A beverage company claims 'Q2 sales dropped' but gives you only one dataset (the transactions table described above) and 45 minutes. Design the analys...
Deploy multi-armed bandits safely
Online bandit with 3 variants, churn guardrail, and delayed conversions Context You are running an online experiment with 3 variants (including contro...
Design a robust conversion propensity model
Daily Notification Propensity Model (Top-20% Targeting) Context You need to score users once per day with the probability they will make a purchase wi...
Diagnose coffee-shop profit decline
You run a single-location coffee shop. In August 2025, profit dropped 18% vs July while transactions fell 4% and average check rose 2%. You have these...
Design video-ads experiment and handle null results
You are launching a new video-ad format. Design an end-to-end A/B test to evaluate it against the current ad format. Be precise: 1) Define exposure an...
Experimentally evaluate jogging-route recommendations
Design an Evaluation for Jogging Route Recommendations in Maps Objective Design an A/B test and evaluation framework for recommending optimal jogging ...
Draft a non-pushy follow-up email
Follow-Up Email After Team-Match (3 Business Days) Context: You are a candidate for a Data Scientist role. Three business days after an onsite team-ma...
Write SQL: sum values ≤ each row’s value
Given table numbers(id INT PRIMARY KEY, val INT), return for every row the sum of all val across the entire table that are ≤ that row’s val (i.e., com...
Write SQL for retention, conversion, and churn
Assume today is 2025-09-01 (use the user's local day boundaries based on users.tz). Given the following schema and sample data, write SQL to: (a) Comp...
Design leakage-free predictive maintenance pipeline
Predict 24-hour Machine Faults from an Hourly Panel (End-to-End Design) Context You are given a machine–hour panel: one row per machine per hour with ...
Calculate break-even new customers for a 30% Rent-a-Home discount
Question Capital One (C1) is evaluating a promotional offer on its Rent-a-Home (RH) product and wants you to size the unit economics. Base assumptions...
Create and query an e-commerce schema
PostgreSQL only. 1) Create these tables with appropriate types and constraints (choose minimal correct types): products(product_id PK, name NOT NULL, ...
Design ETA prediction for Uber rides
System Design: Real‑Time Pickup and Drop‑off ETA Prediction Context: You’re designing an end‑to‑end system that predicts pickup and drop‑off ETAs at t...
Explain your top strengths concretely
Behavioral Prompt: Strengths, STAR Evidence, and 90-Day Application Instructions State your top one or two strengths most relevant to a Senior Data Sc...
Diagnose a failing campaign
Vaccination-Lift Experiment Triage Plan Context: You ran a randomized CRM experiment (e.g., email/SMS/push) to increase vaccination uptake. The overal...
Launch and measure a TV campaign
6-Week Linear TV Experiment to Increase Flu Vaccinations Design a 6-week linear TV campaign and its measurement plan to causally estimate incremental ...
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...
Quantify impact without an A/B test
Stripe-like scenario: You ship a change aimed at increasing payment success rate for APAC merchants, but randomization is infeasible. In ≤6 analyst‑ho...