Data Scientist Interview Questions
Practice 3,064 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."
Should you roll out if NSM decreases?
Scenario You ran an experiment. The north star metric (NSM) is profit per order. Observed results - Average order volume increased in treatment vs con...
Measure free-month promotion impact
You are a data scientist evaluating a one-month free subscription promotion for new users. The business wants to know whether the promotion should be ...
Handle multicollinearity in feature selection
You are building an interpretable predictive model for an insurance company, such as a linear or logistic regression model for claim risk. Several inp...
Implement Factorial and Squares
Write two Python functions for a live coding interview: 1. factorial(n): Given a non-negative integer n, return n!. Implement it iteratively, and be p...
Should DoorDash add bicycle dashers?
DoorDash is considering onboarding bicycle couriers in a dense urban market that currently relies mostly on car or scooter dashers. As a Data Scientis...
Compute variance of a list in Python
Task Given a Python list of numbers (ints/floats), write code to compute its variance. Requirements - Input: nums: list[float] (length \(n\ge 1\)) - C...
Design and analyze a switchback experiment
Switchback Experiment Design: Reducing Cold-Food Incidents for Bike Couriers You are optimizing a delivery marketplace feature suspected to reduce col...
Build and evaluate airline delay prediction model
You are given several CSVs for the classic airline delay challenge with columns like flight_date, carrier, flight_num, origin, dest, sched_dep, sched_...
Implement and extend My Calendar III
Design and implement a booking system like LeetCode 732 (My Calendar III). Provide a class with methods: book(start, end) using half-open intervals [s...
Compute violation rate and flag precision in SQL
You are analyzing a Trust & Safety product in BigQuery. Assume 'today' is 2025-09-01 (UTC). Define precise metrics and write SQL to compute them, bein...
How would you build UberEats ranking?
UberEats wants to improve its recommendation or ranking system for restaurants shown to users on the home feed or in search results. Design the machin...
How would you test a price increase?
You are a data scientist at a B2C AI video editing software company (subscription-based, with a free trial and paid tiers). Product leadership is cons...
Diagnose Decline in Successful Orders
You are a Data Scientist at a food-delivery marketplace. In one geographic market, the number of successful orders has declined over the past 4 weeks....
Evaluate ETA Impact on Conversion
You are a Senior Data Scientist at a ride-hailing company such as Uber. ETA refers to the estimated pickup time shown to a rider before they decide wh...
Build a DNA authenticity classifier
You are given DNA sequences composed of the characters A, C, G, and T. The task is to predict whether a sequence is real biological DNA or a fake / sy...
Design Testing Without A/B Experiments
Suppose a product team wants to evaluate a new feature that is intended to improve user engagement and long-term retention, but a clean randomized A/B...
How would you design delay and watchlist models?
You may be asked one or both of the following machine-learning case questions: 1. Flight-delay prediction case An airline wants a model that predicts ...
Solve Markov, OLS-rotation, and coin-toss probability
Answer the following three interview questions. 1) Basic properties of a Markov (transition) matrix Let \(P\) be a transition matrix of a (time-homoge...
Compute and plot a precision–recall curve
Precision–Recall (PR) curve coding / evaluation You are given a binary classifier’s outputs on a dataset: - y_true: array of true labels in \(\{0,1\}\...
How predict vehicles’ turn direction at intersection?
At an intersection, there are N vehicles stopped or moving slowly. For each vehicle you have historical time-series data up to the current time: - Pos...