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Data Scientist Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
- 9403
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- 546
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- 11
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Showing 421–450 of 1076 results
- GoogleMediumData ScientistDescribe Your Research and Cross-Functional Collaboration Experience
Evaluates behavioral storytelling for research rigor and cross-functional collaboration in data science. Strong answers explain problem framing, methodology, validation, stakeholder alignment, impact, and limitations.
Behavioral & LeadershipTechnical Screen - GoogleMediumData ScientistDesign A/B Test to Isolate Product Usage Drop Causes
Evaluates experimentation strategy for diagnosing a simultaneous product usage drop in the U.S. and Mexico. Strong answers identify confounders, design tests or quasi-experiments, control variables, and report causal lift.
Analytics & ExperimentationTechnical Screen - GoogleMediumData ScientistDesign Scalable Database and Analyze E-commerce Data
This question evaluates relational database design and data-manipulation competencies, including schema modeling and normalization, SQL-based association analysis for co-purchases, and vectorized data transformation using Python/Pandas.
Data Manipulation (SQL/Python)Technical Screen - GoogleMediumData ScientistDesign a scalable video platform database
This question evaluates relational database design and data engineering competencies—including schema modeling, many-to-many relationships, idempotent ingest, indexing and partitioning, OLTP versus analytics integration, GDPR-compliant deletion strategies, and query formulation—within the Data Manipulation (SQL/Python) domain for a Data Scientist role. It is commonly asked to assess both conceptual understanding and practical application of scalable data architectures, performance tuning, and compliance trade-offs, focusing on the ability to reason about schema choices, read/write optimization, and analytics integration without implementation details.
Data Manipulation (SQL/Python)Technical Screen - GoogleHardData ScientistDesign an Unbiased Upgrade Experiment
This question tests the ability to design an A/B test for a software upgrade, specifically focusing on handling non-compliance, selection bias, and the identification of causal effects in a real-world product environment.
Analytics & ExperimentationTechnical ScreenCausal InferenceExperiment DesignA/B Testing - GoogleMediumData ScientistDetermine Impact of New Chat-Notification on User Engagement
Determine Impact of New Chat-Notification on User Engagement evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Statistics & MathTechnical Screen - GoogleEasyData ScientistDetermine Normality of Single Observation with Z-Test
Evaluates hypothesis testing for a single observation against a fully specified standard normal distribution. Strong answers state hypotheses, use z = x, define critical values and p-values, and note limitations.
Statistics & MathTechnical Screen - GoogleHardData ScientistDiagnose Google Meet Disconnections and Assess Business Impact
Evaluates reliability analytics for Google Meet disconnections and enterprise renewal impact. Strong answers define call drops, use client and server logs to localize root causes, estimate account-level retention impact, and prioritize fixes using quantified business risk.
Analytics & ExperimentationTechnical Screen - GoogleHardData ScientistDiagnose and fix flawed model fit
This question tests your ability to diagnose poor model performance in a binary classification task involving imbalanced data, high-cardinality categorical features, and potential bias.
Machine LearningTechnical ScreenClassificationImbalanced DataFeature Engineering - GoogleMediumData ScientistEstimate percentile from buckets
Estimate a percentile from histogram buckets by locating the cumulative-count bucket, explaining why midpoint can be poor, interpolating within the bucket under explicit assumptions, handling log-spaced buckets and edge cases, and reporting uncertainty when buckets are coarse.
Statistics & MathTechnical Screen - GoogleMediumData ScientistEstimate population singletons from a 10% log
This question evaluates mastery of statistical estimation and sampling theory, including recognition of bias from subsampling, frequency‑of‑frequencies modeling for rare events, uncertainty quantification under heavy‑tailed counts, and design of simulation studies.
Statistics & MathTechnical Screen - GoogleMediumData ScientistEstimate unbiased ad scores with many reviewers
This problem tests the ability to design an estimation framework that accounts for rater bias and variance, specifically applying concepts like hierarchical modeling or fixed-effect normalization to estimate latent variables.
Statistics & MathTechnical ScreenStatisticsModelingBias - GoogleHardData ScientistEvaluate AI Workflow Product Metrics
Design an end-to-end measurement and experimentation framework for a generative AI workflow-suggestion tool. Tests metric taxonomy, funnel analytics, instrumentation pitfalls, and causal inference under interference.
Analytics & ExperimentationTechnical Screenexperimentationproduct-metricscausal-inference - GoogleMediumData ScientistEvaluate Auto-Reply Feature Success with Metrics and Experiments
Evaluates metrics and experimentation for an auto-reply suggestion feature in chat. Strong answers define adoption, latency, conversation quality, retention, and safety guardrails, design a causal experiment, and diagnose inconclusive results through funnel, segment, quality, and UI analyses.
Analytics & ExperimentationTechnical Screen - GoogleMediumData ScientistEvaluate Optimal Jogging Routes Feature with A/B Testing
Evaluates A/B test design for Google Maps jogging route recommendations. Strong answers define jogging intent and exposure, measure completed runs and satisfaction, include safety and privacy guardrails, and specify randomization, MDE, power, logging, and rollout criteria.
Analytics & ExperimentationTechnical Screen - GoogleHardData ScientistExperimentally evaluate jogging-route recommendations
This question evaluates competency in experimental design, metric selection and definition, statistical power/MDE calculation, contamination prevention, and operational monitoring for route recommendation features, targeted at Analytics & Experimentation for a Data Scientist role.
Analytics & ExperimentationTechnical Screen - GoogleHardData ScientistExplain Bootstrap and Prove Uniformity
This question tests the conceptual understanding of bootstrap resampling for variance estimation and the mathematical proof of probability distributions using the properties of the Uniform distribution.
Statistics & MathTechnical ScreenStatisticsProbabilityBootstrap - GoogleHardData ScientistExplain Bootstrap and Statistical Inference
This problem tests your understanding of bootstrap resampling theory, confidence interval construction, and the statistical trade-offs involved in hypothesis testing for small-sample experiments.
Statistics & MathTechnical ScreenBootstrapHypothesis TestingMLE - GoogleMediumData ScientistExplain Simpson’s Paradox and Its Causes with Example
Evaluates Simpson's paradox through definition, confounding, subgroup imbalance, and a numeric reversal example. Strong answers compare stratified and aggregate rates and explain when each comparison matters.
Statistics & MathTechnical Screen - GoogleMediumData ScientistExplain and resolve Simpson’s paradox
This question evaluates understanding of Simpson's paradox, confounding, and causal reasoning, checking numerical interpretation of subgroup versus aggregate statistics and the ability to recognize when aggregated averages can mislead.
Statistics & MathTechnical Screen - GoogleMediumData ScientistExplain linear regression to non‑technical stakeholders
This question assesses the ability to communicate complex statistical models to non-technical stakeholders, focusing on clarity, intuition, and identifying limitations.
Machine LearningTechnical ScreenCommunicationLinear RegressionStatistics - GoogleMediumData ScientistGenerate Samples from Truncated Normal Distribution
Evaluates truncated normal distribution fundamentals and sampling methods for lower-tail truncation. Strong answers name the lower-truncated normal, provide the PDF and CDF, and compare inverse-CDF, rejection, and tail-efficient samplers.
Statistics & MathTechnical Screen - GoogleMediumData ScientistGenerate Uniform Samples and Estimate Percentiles
This problem tests the ability to generate uniform spatial samples using standard random functions and the mathematical application of linear interpolation for percentile estimation from binned data.
Statistics & MathTechnical ScreenProbabilityStatisticsInterpolation - GoogleMediumData ScientistIdentify and Fix Predictive Model Performance Gaps
Evaluates predictive-model audit skills across month encoding, feature scaling, and imbalanced classification. Strong answers fix cyclical seasonality, standardize where needed, and adjust losses or thresholds for recall.
Machine LearningTechnical Screen - GoogleMediumData ScientistImplement Sampling and Minimize Loss in Numerical Coding
This question evaluates proficiency in probability and numerical methods, focusing on sampling from truncated distributions and analytical properties of estimators under various loss functions.
Coding & AlgorithmsTechnical Screen - GoogleMediumData ScientistImplement anagram check and stable deduplication
This question evaluates streaming algorithm design, Unicode normalization and locale-aware text processing, multiset frequency counting under tight time and memory bounds for an anagram checker, and stable, order-preserving deduplication with custom keys and NaN handling; it is in the Coding & Algorithms domain for a Data Scientist position.
Coding & AlgorithmsTechnical Screen - GoogleMediumData ScientistImplement percentage RMSE and bootstrap its CI
This question evaluates implementation and statistical reasoning skills, focusing on robust numerical computation of percentage RMSE (including handling zeros/negatives, optional country weights, and numerical stability) and nonparametric bootstrap methods for confidence intervals.
Coding & AlgorithmsTechnical Screen - GoogleMediumData ScientistImplement piecewise linear interpolation for time-to-empty
This question evaluates numerical interpolation, time-series data cleaning, monotonicity preservation, extrapolation, and numerical stability skills applied to battery discharge curves, and falls under coding and algorithms within a data science domain.
Coding & AlgorithmsTechnical Screen - GoogleMediumData ScientistImplement sampling and subarray scan
This question evaluates probabilistic sampling and random-number transformation concepts for generating uniform points in a continuous domain, alongside array-processing and algorithmic analysis skills for identifying the longest strictly increasing contiguous subarray.
Coding & AlgorithmsTechnical Screen - GoogleEasyData ScientistImplement sampling, subarray scan, and percentile estimate
This problem tests your ability to generate random uniform points within a geometric shape, process contiguous array properties using linear scans, and perform linear interpolation on histogram data to approximate percentiles.
Coding & AlgorithmsTechnical ScreenGeometryAlgorithmsStatistics