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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 ScientistInfer 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 ScientistMatch 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 ScientistMeasure 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 ScientistMeasure 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 ScientistMinimize 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 ScientistModel 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 ScientistNarrow 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 ScientistNormalize 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 ScientistPredict 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 ScientistProve 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 ScientistTest 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 ScientistTest 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 ScientistWrite 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 ScientistHow 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 ScientistCritique 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 ScientistOptimize 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 ScientistPredict 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 ScientistBuild 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 ScientistCalculate 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 ScientistCompute 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 ScientistCompute 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 ScientistDescribe 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 ScientistHow 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 ScientistIdentify 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 ScientistInvestigate 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 ScientistCompare 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 ScientistCompare 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 ScientistCount 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 ScientistDerive 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 ScientistSolve 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