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."
Design an A/B for rare cancellations
A/B Test Design: Autoplay-Preview on the Home Page Context: A streaming service is testing an autoplay-preview feature on the home page. Weekly cancel...
Query email logs for deliverability insights
Using the schema and sample data below, write SQL to answer parts a–c. Assume timestamps are UTC. Today is 2025-09-01. Schema: - Emails(sent_id INT, m...
Handle unreliable email during time-critical coordination
Scheduling Under Email Deliverability Risk: 72-Hour Action Plan and Escalation Scenario You must schedule a critical Data Scientist technical screen w...
Determine distribution of aX+b when X~N(0,1)
Linear Transform of a Standard Normal Setup - Let X ~ N(0, 1) (standard normal). - For constants a, b ∈ ℝ, define Y = aX + b. Tasks (a) What is the ex...
Compute daily net users from event logs
Given an event log, write SQL to compute, for the target date 2025‑09‑01 ("today"), the counts of new users, retained users, churn users, and net user...
Handle multiple experiment metrics and communication
Multi‑Outcome Experiment: Decision Framework, Multiplicity, Pre‑registration, and Communication Context You ran an A/B test with: - Primary metric: co...
Determine A/B test sample size drivers
A/B Test Sample Size With Variations and Overdispersed Metric Case You are planning a two‑arm A/B test on a binary conversion metric with: - Baseline ...
Use OrderedDict to dedupe stably
Implement dedupe_preserve_order(seq) that removes duplicates from a list while preserving the order of first appearance, in O(n) time and O(k) space (...
Estimate heterogeneous treatment effects with causal ML
Context You are given large-scale, logged observational data from an always-on promotion. Each record contains features X (user/context), a binary tre...
Design metrics for violating content exposure
Measuring User Exposure to Violating Content on a UGC Platform Context You work on a large-scale user-generated content (UGC) platform that uses autom...
Demonstrate leadership with quantifiable STAR stories
Create Four Concise STAR(L) Stories for a Data Scientist Technical Screen Context You are preparing for a Data Scientist technical screen. Craft four ...
Write SQL for rolling frequency caps
You work on ad serving with per-user rolling 7-day frequency caps at the campaign level. Assume "today" is 2025-09-01 and t0 = 2025-09-01 12:00:00 UTC...
Build the auction status table
You are given three tables for an auction system. Table: buyers - id INT PRIMARY KEY - username VARCHAR Table: lots - id INT PRIMARY KEY - name VARCHA...
Explain factor leakage checks and IC/ICIR filtering
You’re interviewing for a quantitative/alpha role and have built predictive factors (features) for returns. Answer the following (conceptual) question...
Match a string with wildcard pattern recursively
Implement a function that checks whether an input string matches a wildcard pattern. Pattern rules - ? matches exactly one character. - * matches any ...
Write SQL to compute signup and retention lift
You are analyzing an A/B test for a marketing campaign that offers a free 1‑month trial. Assume all timestamps are in UTC. Tables experiment_assignmen...
Choose Metrics for Evaluating Fake-User Classifier
Choose Metrics for Evaluating a Fake-User Classifier A sudden spike in daily average comments may be driven by fake users. You are asked to build a bi...
Analyze Recent User Engagement in Video Calls
calls +-----------+-----------+---------------------+---------+---------+ | caller_id | callee_id | call_start_timestamp| country | call_id | +-------...
Build Trust Quickly with New Team Stakeholders
Build Trust Quickly with New Team Stakeholders This behavioral prompt assesses cross-functional collaboration for a data scientist role. The interview...
Generate Samples from Truncated Normal Distribution
Sampling from a Truncated Normal Distribution You draw from a normal distribution but only keep observations that are at least 1. Assume the original ...