Senior+ Data Scientist Interview Questions
Senior+ data scientist interviews go deep on experimentation and inference, not just SQL and modeling basics. These questions were reported by candidates interviewing for senior+ DS roles, so they reflect what senior+ loops actually push on: A/B test design and analysis, causal inference when you can't run a clean experiment, metric definition and ownership, and the product judgment to turn an analysis into a decision. At the senior+ level interviewers also probe how you think about ML systems end to end — framing, evaluation, and the trade-offs behind a model in production — and how you influence stakeholders with a result. There are 70+ real, recently reported senior+ data scientist questions here across experimentation, statistics, SQL, ML, and case rounds. Most come with a detailed solution or strong-answer guidance so you can calibrate to the senior+ bar.
"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."
Combine noisy thermometers; compute random-walk correlations
Problem 1: Estimating a true temperature from noisy thermometers Assume the true (fixed) temperature is an unknown constant \(\theta\). 1a) One thermo...
How do you resolve partner conflict?
Describe a time you worked with cross-functional partners such as Product, Engineering, Design, Marketing, or another business team on an important pr...
Design a Maps Address Search Bar
Design the search experience for a map application's address bar, similar to the search box in Google Maps. The system should handle multiple user int...
Why does the CLT matter?
The question evaluates a candidate's understanding of the Central Limit Theorem and related competencies in probabilistic reasoning, estimation, and c...
How would you build UberEats ranking?
This question evaluates machine learning and recommender-systems competencies for ranking in a food delivery marketplace, covering problem formulation...
How do you diagnose a ratio metric change
In an A/B test, the treatment group shows a statistically significant increase in a ratio metric: - CTR = clicks / impressions increased by +1.2% rela...
Implement Integer Square Root
Given a non-negative integer x, implement sqrt(x) and return the integer part of its square root, i.e., floor(sqrt(x)). Requirements: - Do not use a b...
Write Queries for Pinterest Engagement Tasks
You are given several data-manipulation tasks based on Pinterest-style product data. Use UTC for all timestamp-to-date conversions unless stated other...
How would you measure impact?
This question evaluates competency in causal inference and experimental design for production analytics, covering delayed outcomes, interference, conf...
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...
Query US-based users and most active forums
You are given user and post data for an online forum platform. Tables (schemas) Assume the following tables: users - user_id BIGINT (PK) - home_countr...
Explain Linear Regression Assumptions
This question evaluates understanding of ordinary least squares linear regression assumptions and their implications for unbiased coefficient estimate...
Simulate Uniform(0,1) from random bits
Assume you have access to a function rand_bit() that returns 0 or 1 with equal probability and independent across calls. How would you generate a rand...
Compute P(A>B) for m- and n-sided dice
Two fair dice are rolled independently: - Die A has m faces labeled \(1,2,\dots,m\). - Die B has n faces labeled \(1,2,\dots,n\). Each face is equally...
Design and analyze pricing-page A/B test
AB Test Plan: New Pricing-Page Layout Context: You will run a 2-arm online experiment on a pricing page. The primary metric is user-level paid convers...
Design Experiments Under Network Interference
You are a Senior Data Scientist for a gaming platform such as PlayStation. Answer the following experimentation questions. 1. A/A test validation: The...
How would you measure billboard impact?
This question evaluates a data scientist's skills in experiment and product design, causal inference (including propensity-score approaches), metric d...
Write SQL for post-trial conversion cohorts
Using the schema below, write SQL to compute, for users first exposed between 2025‑06‑01 and 2025‑06‑30 (inclusive), the intent‑to‑treat paid conversi...
Design fraud detection across channels with unknowns
This question evaluates a data scientist's competence in designing and operationalizing multi-channel fraud detection systems, covering cost-sensitive...
Measure feature impact with switchback, PSM, and CACE
You work at a ridesharing company and want to measure the impact of a new membership feature on rides-per-user (RPU). Across the parts below you will ...