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."
Implement Factorial and Squares
Question In a live coding interview, write two Python functions and be ready to discuss their behavior. 1. factorial(n): Given a non-negative integer ...
Write SQL for geo posting-frequency drops
Using the schema below, write a single ANSI SQL query (window functions allowed) that identifies countries with the largest share of creators whose po...
Transform and aggregate messy event data
Using pandas (vectorized; no loops), clean, combine, and aggregate the following to produce country/plan day-level metrics for 2025-08-31. DataFrames ...
Evaluate Smart Wait Launch Impact
A ride-hailing or autonomous-vehicle product launches a feature called Smart Wait. Before a user confirms a ride, Smart Wait shows a more conservative...
Describe a quantitative market model you built
Question You are interviewing for a quantitative, market-facing Data Scientist role at BlackRock. Answer the following three prompts. 1. Quantitative ...
How would you define and use retention metrics?
Scenario You are a Data Scientist supporting a consumer product (app or website). A PM asks you to “dive deep” on user retention and recommends tracki...
Explain Feature, Model, and Validation Choices
You are interviewing for a Data Scientist role. Describe how you would approach an end-to-end machine learning project on large-scale data. In your an...
Use confusion matrix to choose model metric
Scenario You built a binary classifier (e.g., fraud detection, churn risk, medical screening, spam). You are given a confusion matrix on a validation ...
How to evaluate a new Carousel feature
Context You are a Data Scientist at Pinterest. The product team wants to add a horizontal Carousel module at the top of the Home feed (similar to an I...
Explain PD model validation steps
Validate a Newly Developed Probability of Default (PD) Model Context Assume you have built a retail credit Probability of Default (PD) model with a 12...
Describe ownership and failure
Answer the following behavioral questions in a structured way, using specific examples from your past work or research: 1. Tell me about a time you we...
Can bootstrap help reduce variance
An interviewer asks: “Can bootstrap help reduce variance?” Answer this question precisely. Distinguish between: 1) Using the bootstrap to estimate var...
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...
Describe a high-impact product project
In a conversation with a Head of Product, you are asked to discuss one project in depth. Describe a product or marketplace project where you had meani...
Merge CSVs and build revenue pivot with pandas
You receive four CSVs and must replicate an Excel VLOOKUP + PivotTable workflow using Python/pandas. CSV samples: customers.csv customer_id,signup_dat...
Solve Classic Probability Questions
An onsite interview included the following independent probability and expectation questions: 1. Squid Game bridge problem. In the classic glass-bridg...
Design and evaluate a RAG system
You are interviewing for an L5 Data Scientist role focused on LLM applications. Design a retrieval-augmented generation (RAG) system for an internal q...
Design Siri-vs-GPT query routing
You are a Data Scientist at Apple designing a feature that decides whether a user's natural-language query should be routed to Siri or to a GPT-based ...
Find constant minimizing absolute error
You have a dataset of real-valued targets \(y_1, y_2, \dots, y_n\). You want to fit a constant predictor (no features): - Prediction: \(\hat y_i = c\)...
Write SQL and Python for transaction analytics
You are given user and transaction data. Part A (SQL): Use a join and window functions to answer the prompts below using the following schema and samp...