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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 181–210 of 1076 results

  • CVS HealthHardData Scientist
    Launch and measure a TV campaign

    This question evaluates a data scientist's competency in experimental design and causal inference, including geo-level matching, KPI definition, media measurement (GRP/TRP, reach/frequency, adstock and saturation modeling), power analysis, and operational risk management for measuring incremental vaccinations.

    Analytics & ExperimentationTechnical Screen
  • CVS HealthHardData Scientist
    Lead structured response to accuracy incident

    This question evaluates incident leadership, operational decision-making, and data-driven troubleshooting skills for a data scientist, focusing on triage, hypothesis formation, mitigation choice, cross-functional communication, and recurrence prevention.

    Behavioral & LeadershipTechnical Screen
  • CVS HealthEasyData Scientist
    Reduce LLM hallucination and handle class imbalance

    This question tests your ability to design a robust pipeline for detecting clinical inaccuracies in LLM outputs while managing highly imbalanced datasets where missing a critical diagnosis is costlier than a false alarm.

    Machine LearningTechnical ScreenLLMRAGImbalanced Learning
  • CVS HealthMediumData Scientist
    Tune classifier and compute key metrics

    This question tests your ability to optimize a classification threshold based on business costs and your understanding of how to bridge classification and regression tasks.

    Machine LearningTechnical ScreenClassificationCost-sensitive LearningThresholding
  • CVS HealthMediumData Scientist
    Use pandas to aggregate, pivot, and label

    This question evaluates competency in pandas-based tabular data manipulation—specifically DataFrame merging, groupby aggregation, pivot table construction, counting unique values, and conditional flagging with numpy—within the domain of Data Manipulation (SQL/Python) and is primarily at the practical application level.

    Data Manipulation (SQL/Python)Technical Screen
  • CVS HealthMediumData Scientist
    Write SQL for dedup and purchase shares

    This question evaluates proficiency in SQL data manipulation skills including entity deduplication, canonicalization rules, window functions, common table expressions, joins, and aggregation to derive per-user purchase counts and distributions.

    Data Manipulation (SQL/Python)Technical Screen
  • Capital OneMediumData Scientist
    Analyze ad watch-time with Excel pivots

    This question evaluates a data scientist's proficiency with Excel PivotTables, date and ISO-week handling, aggregation and ratio metrics (clicks per watch-minute), and deterministic tie-breaking logic for reproducible results.

    Analytics & ExperimentationTechnical Screen
  • Capital OneMediumData Scientist
    Articulate your most significant achievement

    This question evaluates a Data Scientist's competency in demonstrating measurable impact, decision-making under constraints, experimental design, trade-off reasoning, and stakeholder management within the Behavioral & Leadership category of data science.

    Behavioral & LeadershipTechnical Screen
  • Capital OneHardData Scientist
    Assess transition and profitability under fossil-fuel constraints

    This question evaluates competency in data-driven energy transition analysis, quantitative modeling of generation mixes, economic pro-formas, and strategic decision-making under regulatory constraints.

    Behavioral & LeadershipTechnical Screen
  • Capital OneMediumData Scientist
    Calculate Longest Transaction Streak for Each User

    This question evaluates proficiency in data manipulation and time-series sequence analysis, specifically measuring the longest run of consecutive successful transactions per user from transactional logs.

    Data Manipulation (SQL/Python)Technical Screen
  • Capital OneMediumData Scientist
    Calculate Profit and Analyze Vegan Burger Market Trends

    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 Calculate Profit and Analyze Vegan Burger Market Trends states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

    Analytics & ExperimentationTechnical Screen
  • Capital OneMediumData Scientist
    Calculate break-even new customers for a 30% Rent-a-Home discount

    A Capital One data-scientist technical screen on break-even and unit economics for a 30%-off Rent-a-Home promotion. You set up and solve the break-even equation for incremental new customers, size it against the 2M cardholder base, then re-solve under spend-uplift assumptions and explain why the required count nearly doubles.

    Statistics & MathTechnical Screen
  • Capital OneEasyData Scientist
    Calculate first-year profit margin

    This question evaluates a data scientist's quantitative reasoning about unit economics and financial metrics, including understanding fixed versus variable costs and computing profit margin as a percentage.

    Statistics & MathTechnical Screen
  • Capital OneEasyData Scientist
    Calculate profit and break-even across pricing models

    This question evaluates understanding of unit economics, break-even analysis, and pricing-model effects on profitability by requiring computation of revenue, variable and fixed costs, and profit under per-GB and two-tier pricing scenarios.

    Statistics & MathTechnical Screen
  • Capital OneHardData Scientist
    Challenge and validate assumptions

    This question evaluates a data scientist's competency in identifying fragile business assumptions, conducting sensitivity analysis, and designing experiments and observational studies to validate parameters related to demand, price elasticity, cannibalization, supply constraints, labor learning curves, regional heterogeneity, and promotional decay.

    Analytics & ExperimentationTechnical Screen
  • Capital OneMediumData Scientist
    Compare Logistic Regression and Random Forest in Python

    Design, evaluate, and contrast a Logistic Regression baseline and a Random Forest model on an imbalanced credit default prediction dataset in Python. Walk through pipeline design, validation strategy, probability calibration, decision thresholding, and production trade-offs.

    Machine LearningTechnical ScreenClassificationModel EvaluationPipelines
  • Capital OneEasyData Scientist
    Compare average profit across mix scenarios

    This question evaluates understanding of expected value, weighted averages, and profit-margin analysis within the Statistics & Math domain for a Data Scientist role. It is commonly asked to probe quantitative reasoning about pricing and cost trade-offs, and it tests practical application of arithmetic and scenario-based profit modeling rather than abstract theoretical concepts.

    Statistics & MathTechnical Screen
  • Capital OneEasyData Scientist
    Compare average unit profit under mix shift

    This question tests the candidate's ability to calculate weighted averages and understand how changes in sales volume distribution (mix shift) affect the overall average profit per unit.

    Statistics & MathTechnical ScreenStatisticsWeighted AverageUnit Economics
  • Capital OneEasyData Scientist
    Compute Groupon unit economics and break-even

    A Capital One data science technical screen case on restaurant unit economics with a Groupon-style voucher. You compute baseline daily profit from a 20-table day, derive the break-even check for a voucher table under a $30-for-$15 offer with a 40% commission, profit a mixed 25-table day, and decompose the profit change into traffic, check size and voucher cost. Full worked arithmetic, a sensitivity solve, and the incrementality follow-ups an interviewer expects.

    Statistics & MathTechnical Screen
  • Capital OneEasyData Scientist
    Compute current annual profit

    This question evaluates numerical proficiency in financial arithmetic, unit-aware quantitative reasoning, and per-customer business-metric computation within a loyalty program context.

    Statistics & MathTechnical Screen
  • Capital OneEasyData Scientist
    Compute incremental profit, breakeven, and revenue sensitivity

    A Capital One data scientist technical-screen case on cost accounting and profitability modeling. Candidates compute the Year-1 incremental profit of a new vegan burger line, decompose it into fixed versus variable components, derive breakeven volume, and run a ±10% sensitivity analysis.

    Statistics & MathTechnical Screen
  • Capital OneMediumData Scientist
    Compute optimal stopping in a die-rolling game

    This question evaluates a candidate's grasp of optimal stopping theory, expected value computation, and finite-horizon decision-making under uncertainty, including recognition of threshold-based policies and backward-induction reasoning relevant to data scientist roles.

    Statistics & MathTechnical Screen
  • Capital OneMediumData Scientist
    Compute partnership profit and break-even population

    This question evaluates competency in analytics and experiment-driven financial modeling, covering unit economics, cannibalization versus true lift, break-even and sensitivity analysis, and interpretation of segment-level impacts on partnership profitability.

    Analytics & ExperimentationTechnical Screen
  • Capital OneMediumData Scientist
    Compute profit and break-even for memberships

    This problem tests your ability to model unit economics for a subscription-based loyalty program and perform sensitivity analysis to determine the break-even point for a business intervention.

    Statistics & MathTechnical ScreenEconomicsLinear ModelingBreak-even Analysis
  • Capital OneMediumData Scientist
    Compute required output to recover 10% investment

    This question evaluates a candidate's ability to perform cost-volume-profit analysis and quantitative financial modeling, assessing skills in algebraic formulation of profit equations, capacity constraint evaluation, and derivation of generalized feasibility formulas.

    Statistics & MathTechnical Screen
  • Capital OneMediumData Scientist
    Compute unit economics and insurance break-even

    This question evaluates a candidate's proficiency in unit economics, insurance break-even analysis, expected-value modeling, churn effects, pricing versus demand trade-offs, and basic statistical inference including MLE and confidence intervals.

    Statistics & MathTechnical Screen
  • Capital OneMediumData Scientist
    Critique a product interface and propose fixes

    This question evaluates a candidate's product-thinking and usability analysis skills, specifically application of heuristics and accessibility standards alongside abilities in redesign proposal, success-metrics definition, and experiment/telemetry planning.

    Behavioral & LeadershipTechnical Screen
  • Capital OneMediumData Scientist
    Critique and Test Python Preprocessing Utilities Effectively

    This question evaluates a candidate's ability to review and critique Python preprocessing utilities, covering competencies in software design patterns (fit/transform separation), coding style and import hygiene, and unit-test specification for data-science pipelines.

    Coding & AlgorithmsTechnical Screen
  • Capital OneMediumData Scientist
    Decide Which Show to Renew

    This problem tests the ability to calculate expected value and ROI for a business decision under uncertainty, requiring the candidate to incorporate subscriber churn risk and lifetime value metrics.

    Analytics & ExperimentationTechnical ScreenExpected ValueROIChurn Analysis
  • Capital OneMediumData Scientist
    Decide and test Groupon program incrementality

    This question evaluates experimental design, causal inference, uplift and profitability modeling, operational risk assessment, and KPI-driven decision rules within the Analytics & Experimentation domain for data scientists, testing both conceptual understanding and practical application of A/B testing, sample-size considerations, and guardrail metrics. It is commonly asked to determine whether a candidate can translate business constraints into a rigorous experiment and profit-oriented analysis, balancing incremental impact estimation, cannibalization concerns, and operational trade-offs to support go/no-go decisions.

    Analytics & ExperimentationTechnical Screen