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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 451–480 of 1076 results

  • GoogleMediumData Scientist
    Infer distribution and choose robust statistics

    This problem tests the ability to diagnose non-normal data distributions (specifically zero-inflated, heavy-tailed data) and select appropriate statistical metrics for hypothesis testing.

    Statistics & MathTechnical ScreenStatisticsData DistributionsHypothesis Testing
  • GoogleMediumData Scientist
    Match payments to invoices by memo or amount

    This problem tests string parsing, hash-map based data indexing, and multi-criteria reconciliation logic (fuzzy matching via IDs vs. exact matching via amount).

    Coding & AlgorithmsTechnical ScreenHashingStringsData Reconciliation
  • GoogleMediumData Scientist
    Measure Bird Species Segregation

    This question evaluates spatial statistical reasoning, ecological data analysis, and the ability to formulate hypotheses, choose appropriate segregation metrics, and account for confounders and sampling bias.

    Statistics & MathTechnical Screen
  • GoogleHardData Scientist
    Measure outage impact; choose fix vs build

    This question evaluates instrumentation design, telemetry analysis, causal impact estimation, failure deduplication, and decision-making under uncertainty for a Data Scientist, testing competencies in analytics, experimentation, and product-metric prioritization.

    Analytics & ExperimentationTechnical Screen
  • GoogleMediumData Scientist
    Minimize L2, L1, and quantile losses

    This question evaluates understanding of statistical estimators and optimization principles for L2, L1, and tilted absolute (quantile) loss functions, including use of derivatives and subgradients, order-statistics, algorithmic complexity, and robustness considerations.

    Coding & AlgorithmsTechnical Screen
  • GoogleHardData Scientist
    Model Soccer Shot Conversion

    This problem tests the ability to design an end-to-end predictive model for sports events, focusing on feature engineering, handling spatial data sparsity, and evaluating probabilistic outputs.

    Machine LearningTechnical ScreenLogistic RegressionModel CalibrationFeature Engineering
  • GoogleMediumData Scientist
    Narrow a confidence interval for a mean

    This question evaluates understanding of confidence intervals, the relationship between sample size and interval width, variance-reduction techniques, the impact of changing confidence levels, and the ability to communicate statistical risk and design-based trade-offs.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Normalize Columns in Binomial Matrix Efficiently

    This question evaluates proficiency in matrix manipulation, handling of binomial random samples, column normalization, and algorithmic efficiency for processing large numerical arrays.

    Coding & AlgorithmsTechnical Screen
  • GoogleHardData Scientist
    Predict and act on contract renewal risk

    This question evaluates competency in applied machine learning for enterprise churn prediction, testing skills in problem framing, feature engineering, model selection, data hygiene, evaluation metrics, and decisioning within the Machine Learning domain.

    Machine LearningTechnical Screen
  • 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
    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
    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
    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
    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
    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
  • HeadlandsMediumData Scientist
    Compare Candy-Color Guessing Experiments with Different Sample Sizes

    Evaluate and compare evidence from two binomial experiments with different sample sizes and hit rates against a random guessing null hypothesis.

    Statistics & MathTechnical Screenstatisticshypothesis-testingbinomial-distribution
  • Hudson River TradingMediumData Scientist
    Compare Mean and Median for a Distribution with a Point Mass

    This question tests the theoretical and empirical comparison between the sample mean and sample median on a mixture distribution containing a discrete point mass and a Gaussian component.

    Statistics & MathTechnical Screenstatisticsprobabilityestimation
  • Hudson River TradingMediumData Scientist
    Count inversions in a permutation

    This question evaluates understanding of inversion counting in permutations, testing algorithmic problem-solving, complexity analysis, and data-structure reasoning about pairwise order relations.

    Coding & AlgorithmsTechnical Screen
  • Hudson River TradingMediumData Scientist
    Derive expected inversions and mean distribution

    This problem tests your understanding of linearity of expectation and variance properties applied to permutation statistics, as well as the ability to design a simulation to verify analytical derivations.

    Machine LearningTechnical ScreenProbabilityStatisticsExpectation
  • Hudson River TradingMediumData Scientist
    Solve Dice Probability and Matrix Questions

    This problem tests probability distributions over modular arithmetic and the identification of properties of doubly stochastic matrices.

    Machine LearningTechnical ScreenProbabilityLinear AlgebraMatrices