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."
Write rolling-window SQL over weekly cohorts
You have two tables: users and transactions. Write a single SQL query (use CTEs) to produce, for each calendar week and user, weekly_revenue, a 4-week...
Build predictive model for feature rollout targeting
Before global launch, you want to predict which users or products would benefit most from the 'More like this' button so you can stage rollout. Design...
Quantify launch decision with tests and guardrails
You will formalize the statistical decision rules for the Instagram button experiment described above. Given: baseline exploration rate (p0) = 0.15 pe...
Write SQL to detect recurring non-subscription users
You have two tables: merchant and transaction. Assume 'today' is 2025-09-01. Schema: merchant(merchant_id INT PK, merchant_name TEXT, country TEXT, cr...
Merge seven tables into one clean DataFrame
Using pandas only (no loops over rows), write a function build_facts(customers, orders, order_items, products, payments, shipments, refunds) -> pd.Dat...
Query top spenders and 7-day growth
Assume 'today' = 2025-09-01. Write a SQL query to: (1) for each model, compute total revenue in the last 7 days (2025-08-26 to 2025-09-01 inclusive) a...
Manipulate and merge DataFrames correctly
Given three pandas DataFrames: customers customer_id, join_date, tier 101, 2025-01-02, gold 102, 2025-02-10, silver 103, 2025-03-05, gold products mod...
Compute French DAU video-call percentage yesterday
Compute the percentage of daily active users (DAU) from France who were on at least one video call yesterday (2025-08-31 UTC). DAU is defined as users...
Compute callers contacting >3 people last 7 days
Using the schema below, write a single SQL query to return the number of unique callers who started calls with more than 3 distinct other users during...
Load and visualize large CSV robustly
You're screen-sharing in a HackerRank environment with Python 3, pandas, numpy, seaborn, and matplotlib available. You are given a single file data.cs...
Communicate and de-risk a non-experimental launch
Decision-to-Launch Plan After a Synthetic Control Result Context You are a data scientist who used a Synthetic Control method to estimate the causal i...
Derive paying users over time with churn
Leaky-Bucket Model of Paying Users Context - Time is discrete by month t = 1, 2, ... - Each month t: - N new users start a free trial. - a (fracti...
Write SQL for dedup and purchase shares
You are given two tables with intentional duplicates. Write SQL to: (a) identify duplicate user_ids and produce a canonical, deduplicated users set; (...
Write SQL to analyze Group Calls adoption
Write SQL (assume PostgreSQL) to analyze Group Calls adoption and cannibalization. Use this schema and sample data. Schema: - users(user_id INT PRIMAR...
Validate needs and benchmark competitor adoption
Research Plan: Validate User Needs and Benchmark Competitors' Adoption of Group Calling You are designing a research plan for a consumer communication...
Choose group-call size cap via experiment
Decide the Maximum Participants per Group Call: Experiment Plan Context: You need to choose a default cap for group calls (maximum concurrent particip...
Write SQL for initiators and French DAU%
You are given the following PostgreSQL tables. Assume all timestamps are UTC and "today" is 2025-09-01. For any reference to "last 7 days," use the in...
Design an analytic warehouse for event data
Design a warehouse-ready analytics data model and ingestion plan to support cohort retention, ARPU, and product-case analyses at scale (50M events/day...
Decide if subgroup increases imply overall increase
TikTok Time: Subgroup Increases vs Overall Average (Simpson's Paradox) You are analyzing average daily time spent on TikTok by gender (male, female) a...
Measure PMF for Alexa Shopping
Define and Measure Product–Market Fit (PMF) for Alexa Shopping Context You are designing a measurement plan to assess PMF for Alexa Shopping, where cu...