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."
Decide under adverse signals and conflicts
Scenario: Pre-Launch Decision Under Mixed Signals You are preparing to launch a new messaging/notifications feature. Leading indicators are mixed: som...
Compute and rank top bad advertisers
SQL on ad safety. Assume the following schema and sample rows. Use ANSI SQL. Today is 2025-09-01; interpret “last 7 days” as 2025-08-26 00:00:00 to 20...
Derive E[X^2] from mgf e^{t^2}
Identify Distribution and Compute E[X^2] from an MGF You are given a random variable X with moment-generating function (mgf): - M_X(t) = E[e^{tX}] = e...
Describe a project you’re most proud of
Describe the project you’re most proud of using the STAR method. Specify the exact goal and success metrics up front; quantify at least two outcomes (...
Diagnose a sudden KPI drop and validate causes
A core KPI (comments_per_DAU) suddenly drops materially. Outline a structured root-cause analysis and validation plan. a) Scoping and sanity: Quantify...
Analyze DAU comments distribution and resampling
Consider the metric comments_per_DAU (number of comments a daily active user makes in a day). a) Shape: Describe and justify the expected distribution...
Design and validate ad model launch
You are on the Ads team and just trained a new ad recommendation model meant to replace the current model in production. Design a rigorous plan to dec...
Compute sample size and significance
You are planning a two-variant A/B test with equal allocation and a binary primary metric (conversion). Baseline rate p0 = 0.045. You want to detect a...
Plan an experiment to validate targeting impact
You produced a ranked list of merchants predicted to adopt Subscription. Design an experiment to validate business impact of targeting them with a sal...
Build and validate a binary classifier
ML Pipeline with Grouped CV, Imbalance Handling, Calibration, and Thresholding Context: You have a labeled dataset where the target is is_active_30d (...
Build dashboard; diagnose engagement–purchase gap
Build a Comprehensive Dashboard for the Shopping Tab (Organic Only) Context Assume the Shopping tab is an in-app surface for organic product discovery...
Produce dating profile funnel report by cohort
You work on a dating app. Produce a daily profile-funnel report for 2025-08-25 through 2025-09-01 inclusive, with one row per day, gender, and age_buc...
Implement randomized Quickselect without k-shift bug
Implement randomized Quickselect to return the k-th largest element (1-based k, 1 ≤ k ≤ n) from an unsorted integer array. Use an in-place partition t...
Compute 95th-percentile call concurrency
Given N call sessions as half-open intervals [start, end) in UNIX seconds, design an algorithm to compute the 95th percentile of per-minute concurrent...
Write SQL for 7-day WhatsApp call metrics
Today is fixed as 2025-09-01. Using PostgreSQL, write a single query that returns one row per UTC calendar date for the last 7 days inclusive of today...
Tune classifier and compute key metrics
Payment Error Classifier — Evaluation, Thresholding, and Cost-Sensitive Design Context You built a binary classifier to flag incorrect payments (posit...
Compute daily work hours from in/out events
Given punch events, compute each employee’s daily hours, handling unmatched events and overnight shifts. Write SQL over: events(employee_id INT, evt_t...
Build a package-allocation model for couriers
Automatic Package-to-Courier Assignment with ML + Optimization You previously assigned packages to couriers manually. Design an end-to-end system that...
Design experiments and observational alternatives
Stories Consumption Analysis and Causal Inference Tasks Context: You are a data scientist evaluating why Stories consumption appears higher on Faceboo...
Derive and validate DID for staggered rollout
Causal Effect of a Staggered Adoption Policy Across EU Regions You cannot randomize. An intervention is rolled out at different dates across EU region...