Katkat

practice a little every day, paws crossed ♡

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 301–330 of 344 results

  • UberMediumData Scientist
    Analyze Cancellation Change with Statistics

    This question evaluates statistical inference for binary outcomes, regression adjustment for confounding, experiment design and power analysis, and nonparametric uncertainty estimation using bootstrapping, and is targeted at Data Scientist roles within the Statistics & Math domain.

    Statistics & MathTechnical Screen
  • UberHardData Scientist
    Apply instrumental variables under interference

    This question evaluates understanding of causal inference with instrumental variables in the presence of interference, testing skills in defining units and aggregation levels for market‑level spillovers, articulating IV assumptions (relevance, exclusion restriction, independence, monotonicity), and formulating estimation frameworks such as two‑stage least squares. Commonly asked in Statistics & Math interviews for data scientist roles because networked marketplaces invalidate simple A/B tests, it sits in the econometrics/causal inference domain and primarily assesses practical application of IV methods while requiring conceptual understanding of identification, robustness diagnostics, and sensitivity analysis.

    Statistics & MathTechnical Screen
  • UberMediumData Scientist
    Compare Two Coin Proportions

    This question evaluates proficiency in statistical inference for proportions, including hypothesis formulation, comparison of two independent samples, confidence interval interpretation, and interpretation of p-values and sampling variability.

    Statistics & MathTechnical Screen
  • UberHardData Scientist
    Compute A/B sample size under clustering

    This question evaluates competency in experimental design and statistical inference for A/B testing, specifically sample size calculation for two-sample proportions with unequal allocation, clustering effects (ICC and design effect), and adjustments for bot removal and data-quality attrition.

    Statistics & MathTechnical Screen
  • UberMediumData Scientist
    Derive a CDF from a PDF

    This question tests the ability to derive a Cumulative Distribution Function (CDF) from a given Probability Density Function (PDF), ensuring proper integration and boundary conditions.

    Statistics & MathTechnical ScreenProbabilityCalculusStatistics
  • UberHardData Scientist
    Design an A/B test; choose Z vs T

    This question evaluates a candidate's competency in experimental design and statistical inference, covering sample-size and power calculations, the choice between Z and T tests, sequential testing/alpha-spending strategies, and causal-inference planning for non-randomized rollouts.

    Statistics & MathTechnical Screen
  • UberMediumData Scientist
    Formulate OR model to reduce driver backtracking

    This question evaluates skills in defining a quantitative driver-backtracking metric from GPS and assignment logs, detecting and validating backtracking segments, and formulating constrained optimization models for dispatch and repositioning, drawing on statistics, operations research, and stochastic optimization.

    Statistics & MathOnsite
  • UberHardData Scientist
    Formulate hypotheses and compute AB test significance

    This question evaluates a data scientist's competency in experimental design and statistical inference for A/B testing, covering hypothesis formulation, difference-in-proportions testing and confidence intervals, guardrail analysis, multiple-testing correction, interim alpha-spending approaches, and variance-reduction techniques such as CUPED.

    Statistics & MathTechnical Screen
  • UberHardData Scientist
    Measure rider incentive causal ROI

    This question evaluates a data scientist's competency in causal inference and experimental design, marketplace health metric construction, ROI estimation, and the handling of selection bias, spillover effects, multiple testing, and heterogeneity in two-sided platforms.

    Statistics & MathTechnical Screen
  • UberMediumData Scientist
    Should Uber double member discounts?

    This problem tests your ability to design a controlled experiment for a two-sided marketplace and evaluate whether a discount-doubling strategy is statistically and economically viable.

    Statistics & MathTechnical ScreenA/B TestingCausal InferenceMarketplace Economics
  • UpstartMediumData Scientist
    Analyze HT vs HH stopping-time probabilities

    This question evaluates understanding of discrete probability, stopping-time analysis, pattern occurrence in Bernoulli sequences, derivation of PMFs and expectations, and the ability to generalize results to biased coins.

    Statistics & MathTechnical Screen
  • UpstartEasyData Scientist
    Assess Probability of Heads in Coin Tosses

    Assess Probability of Heads in Coin Tosses 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 & MathOnsite
  • UpstartEasyData Scientist
    Calculate Expected Streaks in Coin Toss Sequence

    Calculate Expected Streaks in Coin Toss Sequence 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 & MathOnsite
  • UpstartEasyData Scientist
    Calculate Particle Survival Probability After Time t

    This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Calculate Particle Survival Probability After Time t states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Statistics & MathTechnical Screen
  • UpstartEasyData Scientist
    Combine noisy thermometers; compute random-walk correlations

    This question evaluates estimation and probabilistic reasoning skills, specifically the construction of unbiased estimators and variance-minimizing linear combinations for combining noisy measurements, together with computation and asymptotic characterization of correlations in a 2D simple random walk.

    Statistics & MathOnsite
  • UpstartEasyData Scientist
    Compute decay, OLS, and classic probability results

    This question evaluates probability and statistical modeling skills—probabilistic reasoning for exponential decay and the coupon-collector expectation, derivation of population OLS coefficients for simple linear models, simulation implementation, and conditional probability reasoning exemplified by the Monty Hall scenario.

    Statistics & MathOnsite
  • UpstartEasyData Scientist
    Correct length-biased sampling from family-size survey

    This question evaluates understanding of length-biased sampling and inference under sampling bias, specifically how sampling by individuals (children) differs from sampling by households when estimating family-size probabilities.

    Statistics & MathTechnical Screen
  • UpstartEasyData Scientist
    Determine distribution of aX+b when X~N(0,1)

    This problem tests your understanding of how linear (affine) transformations affect the properties of a normal distribution and the derivation of its mean and variance.

    Statistics & MathHR ScreenStatisticsProbabilityNormal Distribution
  • UpstartMediumData Scientist
    Estimate Family Proportions and Explain Regression Anomalies

    Estimate Family Proportions and Explain Regression Anomalies 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 & MathOnsite
  • UpstartMediumData Scientist
    Estimate and Derive Regression Coefficient for X on y

    Estimate and Derive Regression Coefficient for X on y 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 & MathOnsite
  • UpstartEasyData Scientist
    Identify binomial model and compute moments

    This question tests the ability to identify a binomial process, express its probability mass function, and derive its fundamental moments (mean and variance).

    Statistics & MathHR ScreenStatisticsProbabilityBinomial Distribution
  • UpstartMediumData Scientist
    Solve core probability/statistics mini-problems

    Category: Statistics & Math; this prompt evaluates core probability and statistical concepts — exponential decay and discrete survival counts, Bayesian updating, properties of population OLS coefficients, conditional-probability reasoning exemplified by Monty Hall, the coupon-collector expected time, and the conceptual distinction between likelihood and probability — relevant for Data Scientist roles. It is commonly asked because it probes foundational distributional intuition, independence and conditional inference, and expectation/estimation at an introductory-to-intermediate theoretical level that underpins applied modeling and experimental interpretation.

    Statistics & MathOnsite
  • UpstartMediumData Scientist
    Solve drunk-passenger probability and simulate outcome

    This question evaluates probabilistic reasoning and stochastic-process intuition, including use of invariant arguments, closed-form derivations, statistical estimation via Monte Carlo simulation, and analysis of algorithmic time and space complexity.

    Statistics & MathTechnical Screen
  • Virtu FinancialMediumData Scientist
    Compute probability in urn with green returns

    Compute probability in urn with green returns 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
  • Virtu FinancialMediumData Scientist
    Compute probability with colored balls draws

    This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Compute probability with colored balls draws states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Statistics & MathTechnical Screen
  • VoleonHardData Scientist
    Compute robust inference under skew and outliers

    This problem tests your ability to design a robust statistical framework for comparing two groups with highly skewed, heavy-tailed data and potential outliers, moving beyond simple t-tests.

    Statistics & MathTechnical ScreenStatisticsA/B TestingRobust Inference
  • VoleonMediumData Scientist
    Diagnose and interpret regression assumptions

    This problem tests your ability to diagnose violations of OLS assumptions in count data and determine the appropriate corrective modeling strategy.

    Statistics & MathTechnical ScreenRegressionGLMDiagnostics
  • VoleonMediumData Scientist
    Explain P-Value Reporting and Bootstrap for Coefficient Estimation

    This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Explain P-Value Reporting and Bootstrap for Coefficient Estimation states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Statistics & MathTechnical Screen
  • VoleonEasyData Scientist
    Solve Markov, OLS-rotation, and coin-toss probability

    This multi-part question evaluates understanding of Markov chain and stochastic matrix properties, linear-algebra facts about eigenvalues and stationary distributions, invariance and sampling-distribution properties of OLS under orthonormal rotations, and discrete stopping-time probability reasoning for coin-flip processes.

    Statistics & MathTechnical Screen
  • Walmart LabsMediumData Scientist
    Understand Propensity Score Matching in Business Analytics

    This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Understand Propensity Score Matching in Business Analytics states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Statistics & MathOnsite