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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Design metrics and experiment for Shopping launch
Experiment and Metric Plan: New Shopping Module Embedded in the Pins Feed Context You are introducing a Shopping module directly into the Pins feed. T...
Implement lower_bound on unknown-size sorted array
Lower Bound in Unknown-Length Nondecreasing Array via API Setup You are given a non-decreasing integer array A of unknown length n. You cannot access ...
Diagnose a 10% DAU drop
On-Call Incident: Yahoo Mail DAU Down 10% on 2025-09-01 Assume all times are UTC, the product is global, and DAU is the canonical daily active user me...
Evaluate a model and choose metrics
Fraud-screening model evaluation under class imbalance and asymmetric costs Context You operate a binary classifier that flags e‑commerce orders for m...
Relate coefficients under linear feature transformation
Answer both parts. Part 1: Coefficients under feature transformation You have original predictors \(x_1, x_2\) and define transformed predictors: - \(...
Design tests to measure latency impact
Question You are a Data Scientist supporting a large consumer product (e.g., YouTube). Engineering ships a change intended to reduce client-side / vid...
Choose single queue vs multiple queues
Bank queue design choice A bank has 5 tellers. Two possible customer-flow designs: 1. Single queue: one common line feeding the next available teller ...
How to evaluate adding video ads in a game
Case study: Evaluate adding video ads to a mobile game You are the Data Scientist for a free-to-play mobile game. The product team wants to add video ...
Diagnose Cold Food Deliveries with Key Metrics Analysis
Diagnosing and Testing Solutions for Cold Food Deliveries Scenario You are a data scientist at a food-delivery marketplace experiencing a spike in cus...
Implement stack variants and upward path sum
Question Answer the following coding questions. They progress from augmented stacks to streaming statistics to tree path reasoning. 1. MinStack — Desi...
Write SQL for seller and category metrics
Assume the following marketplace tables. Table: listing_interactions - buyer_id STRING - seller_id STRING - product_id STRING - interaction_date DATE ...
How do you resolve stakeholder conflict?
For a Staff Data Scientist role, describe how you work with cross-functional partners such as product managers, engineers, and business leaders. Give ...
Diagnose Decline in Delivery Success: Data, Hypotheses, Tests
Diagnose a 10% Drop in Successful Deliveries Scenario You manage a territory in a food-delivery marketplace and observe that the number of successful ...
Determine Success Metrics for Biker Dasher Program Launch
Scenario DoorDash is considering a 'Biker Dasher' program to let couriers use bicycles (and e-bikes) for deliveries in dense urban areas. You are the ...
Diagnose rising cold-food complaints and choose metrics
Case: Customers complain food arrives cold You are a Data Scientist (Analytics-focused) at a food delivery marketplace (e.g., DoorDash). Over the last...
Measure App Store success and debug funnel anomaly
Part A — Product case: measuring success for a new App Store Shopify is launching a Shopify App Store where merchants can browse/install apps built by...
Compute Piecewise Linear Interpolation
You are given an unsorted list of distinct 2D points (x_i, y_i). When the points are sorted by x_i, connecting adjacent points forms a polyline. Given...
Design an Uber feature and analyze safety
You are interviewing for a Data Scientist summer internship at a ride-sharing marketplace. Part A: Product case Uber wants ideas for a new rider-facin...
Write SQL for reply-based recipient metrics
You work on a social product and are given two tables. Assumptions (use these unless you state otherwise): - All timestamps are in UTC. - A “reply” is...
How would you evaluate adding video ads?
You are a data scientist for a free-to-play mobile game. The product team wants to introduce video ads (e.g., rewarded videos and/or interstitial vide...