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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
Questions
546
Companies
11
Topics
8
Languages

Showing 811–840 of 1971 results

  • GoogleMediumData Scientist
    Prove OLS invariance to linear transforms

    This question evaluates understanding of linear regression invariance under invertible linear transformations, multivariate linear algebra, and the impact of regularization (ridge and lasso) on coefficient and prediction stability in the Statistics & Math domain.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Reading a Regression Slope: P-values, Intervals, and Causality

    Use a fitted slope from a one-predictor regression to explain precisely what a p-value and a confidence interval mean, what assumptions they rest on, how confidence and prediction intervals differ, and why significance is not causation. Tests statistical precision under interview pressure.

    Statistics & MathOnsitestatisticslinear-regressionhypothesis-testing
  • GoogleMediumData Scientist
    Reflect on a failed decision and redo it

    This question evaluates decision-making, ownership, risk assessment, stakeholder management, product impact analysis, and post‑mortem reflection competencies relevant to data scientists.

    Behavioral & LeadershipOnsite
  • GoogleMediumData Scientist
    Resolve Team Disagreement on Off-Site Activity Choice

    This interview question evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer for Resolve Team Disagreement on Off-Site Activity Choice states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Behavioral & LeadershipOnsite
  • GoogleHardData Scientist
    Resolve conflict on trust versus growth priorities

    This question evaluates a candidate's competency in conflict management, stakeholder mapping and alignment, risk assessment for content safety, reversible experiment and phased rollout design, and respectful escalation under time pressure.

    Behavioral & LeadershipOnsite
  • GoogleEasyData Scientist
    Select MOST/LEAST appropriate actions (SJT)

    This question evaluates situational judgment, ethical decision-making, and adherence to data confidentiality and respectful workplace policies relevant to a Data Scientist role.

    Behavioral & LeadershipOnsite
  • GoogleMediumData Scientist
    Simulate Coin Flips to Determine Fairness via Empirical Distribution

    This question evaluates a candidate's ability to perform simulation-based hypothesis testing by implementing Monte Carlo sampling and computing an empirical two-sided p-value from observed coin-flip counts, emphasizing statistical computation and numerical accuracy.

    Coding & AlgorithmsOnsite
  • GoogleMediumData Scientist
    Simulate Uniform(0,1) from random bits

    This Coding & Algorithms question for a Data Scientist evaluates understanding of randomized algorithms, bit-level representation of real numbers, and probabilistic error and time-complexity analysis, situated at an algorithmic and mathematical abstraction level that requires both conceptual design and quantitative reasoning.

    Coding & AlgorithmsOnsite
  • GoogleMediumData Scientist
    Test a coefficient and explain t-distribution

    This question evaluates a candidate's competence in statistical inference for linear regression—specifically hypothesis testing for OLS coefficients, construction of t-statistics, estimation of standard errors, and the role of estimated error variance—within the Statistics & Math domain for Data Scientist roles.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Test if one value comes from N(μ,σ²)

    This question tests the ability to perform statistical hypothesis testing on a single observation, evaluate the limitations of small sample sizes, and explain the trade-offs between Type I and Type II errors.

    Statistics & MathTechnical ScreenStatisticsHypothesis TestingNormal Distribution
  • GoogleMediumData Scientist
    Understand Simpson's Paradox with Simple Examples

    This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Understand Simpson's Paradox with Simple Examples states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Statistics & MathOnsite
  • GoogleMediumData Scientist
    Write SQL/Python for messy event data

    This question evaluates SQL and pandas proficiency for event-level data manipulation, including time zone–aware local date conversion, session-based deduplication, cohort and conversion metric calculation, and basic experiment sanity checking via a sample-ratio-mismatch p-value.

    Data Manipulation (SQL/Python)Technical Screen
  • GrindrMediumData Scientist
    Evaluate Dating App Product Changes

    This question tests the ability to design an A/B test for a two-sided marketplace, focusing on network effects, cannibalization of metrics, and the selection of hold-out groups to measure long-term user behavior.

    Analytics & ExperimentationOnsiteA/B TestingMarketplace AnalyticsCausal Inference
  • GrindrMediumData Scientist
    How would you evaluate causal lift and a paywall change?

    A two-part Grindr Data Scientist technical screen on analytics and experimentation. Part 1 designs an advertiser-level causal study for a new ad-optimization product when the eligible advertiser pool is too small, covering MDE/power, CUPED, matched-pair and panel designs, interference, and heterogeneous effects. Part 2 evaluates lowering a free-user paywall from 100 to 80 profiles, balancing short-term conversion against long-term LTV, retention, ad revenue, and one-sided-triggering selection bias.

    Analytics & ExperimentationTechnical Screen
  • GsaMediumData Scientist
    Critique a CNN-Based Bridge Safety Proposal

    This question tests the ability to identify flaws in a computer vision project, focusing on data validity, label sparsity, adversarial robustness, and the practical limitations of predictive modeling in structural engineering.

    Machine LearningTechnical ScreenComputer VisionAdversarial MLData Ethics
  • GsaHardData Scientist
    Optimize Matrix-Chain Multiplication

    This problem tests your ability to solve a classic dynamic programming challenge, focusing on finding the optimal order of matrix multiplications to minimize the total number of scalar operations.

    Coding & AlgorithmsTechnical ScreenDynamic ProgrammingAlgorithmsOptimization
  • GsaHardData Scientist
    Predict Stock Returns from Sentiment and Market Data

    This problem tests the ability to design an end-to-end predictive pipeline for stock returns, focusing on time-series integrity, feature engineering, and robust evaluation metrics.

    Machine LearningTechnical ScreenFinancial ModelingTime SeriesData Leakage
  • GustoMediumData Scientist
    Build Churn Prediction and Survival Models

    This problem tests the ability to design an end-to-end churn prediction pipeline, specifically focusing on the distinction between binary classification and survival analysis in the context of customer retention.

    Machine LearningTechnical ScreenChurn PredictionSurvival AnalysisFeature Engineering
  • GustoMediumData Scientist
    Build a Churn Prediction Model

    This question tests the ability to design an end-to-end churn prediction pipeline, focusing on temporal data integrity, class imbalance, and actionable evaluation metrics for business stakeholders.

    Machine LearningOnsiteChurnFeature EngineeringImbalanced Data
  • GustoMediumData Scientist
    Calculate Net Pay Change for Q1 2023 Decreases

    This question evaluates a candidate's data-manipulation competency in SQL and Python, focusing on computing net pay, aggregating over a calendar quarter, and measuring percentage change between recent pay periods.

    Data Manipulation (SQL/Python)Technical Screen
  • GustoMediumData Scientist
    Compute Parking Clustering Probability and P-Value

    This question tests your ability to calculate exact combinatorial probabilities under a null hypothesis and define a p-value for a spatial clustering test.

    Statistics & MathTechnical ScreenProbabilityCombinatoricsHypothesis Testing
  • GustoEasyData Scientist
    Compute p-values for 2 variants vs control

    This question evaluates a candidate's competence in statistical hypothesis testing and experiment analysis, focusing on A/B/n comparison of conversion rates, p-value computation, confidence interval estimation for lift, multiple-testing considerations, and interpretation of results.

    Analytics & ExperimentationTechnical Screen
  • GustoMediumData Scientist
    Define Churn and Design Onboarding Experiment

    This question tests the ability to define business-relevant churn metrics for a SaaS platform and design a controlled experiment to optimize user onboarding.

    Analytics & ExperimentationOnsiteAnalyticsExperimentationMetrics
  • GustoMediumData Scientist
    Describe Your Analytical Experience and Cross-Functional Collaboration.

    This interview question evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer for Describe Your Analytical Experience and Cross-Functional Collaboration. states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Behavioral & LeadershipTechnical Screen
  • GustoMediumData Scientist
    How do you test two variants vs control?

    This question evaluates proficiency in A/B/n experimentation, hypothesis testing for binomial proportions, multiple-comparison correction methods, confidence interval estimation for conversion uplift, and experiment-related decision-making in the Analytics & Experimentation domain at an applied/intermediate statistical-analysis level.

    Analytics & ExperimentationTechnical Screen
  • GustoMediumData Scientist
    Identify Growth Opportunities for New Payroll Feature Launch

    This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Identify Growth Opportunities for New Payroll Feature Launch states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Analytics & ExperimentationTechnical Screen
  • GustoMediumData Scientist
    Investigate Causes of Increased Payroll Processing Time

    This interview question evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer for Investigate Causes of Increased Payroll Processing Time states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Analytics & ExperimentationTechnical Screen
  • HBOHardData Scientist
    Define scalable train/validation for churn

    This question assesses the ability to design an end-to-end churn prediction pipeline, focusing on temporal integrity, handling class imbalance, and ensuring robust production deployment.

    Machine LearningOnline AssessmentChurnSystem DesignData Leakage
  • HBOHardData Scientist
    Design an A/B for rare cancellations

    This question evaluates a data scientist's competency in experimental design, rare-event power analysis, precise metric and guardrail definitions, variance-reduction covariate adjustment, sequential-testing decisions, monitoring/dashboard specification, and interpretation of heterogeneous treatment effects.

    Analytics & ExperimentationOnline Assessment
  • HeadlandsMediumData Scientist
    C++ Sliding-Window Mean of a Float Array With Inf, -Inf and NaN Handling

    Implement an O(n) sliding-window mean over a 32-bit float array containing IEEE-754 special values (+inf, -inf, NaN) without poisoning subsequent windows or suffering numerical drift.

    Software Engineering FundamentalsOnline Assessmentcppsliding-windowieee-754