Data Scientist Interview Questions

Showing 1501–1530 of 1971 results

• RobinhoodEasy·Data Scientist
  Design an experiment to launch fractional shares

  This question evaluates a candidate's competency in experimentation design, product analytics, statistical power and sample-size calculation, causal inference, and risk identification within a brokerage product context.

  Analytics & ExperimentationOnsite
• RobinhoodMedium·Data Scientist
  Diagnose Decline in First Day Funding Rate

  Diagnose Decline in First Day Funding Rate evaluates metric design, causal reasoning, experiment setup, diagnostics, SQL/statistical checks, and recommendations in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  Analytics & ExperimentationTechnical Screen
• RobinhoodMedium·Data Scientist
  Identify Overlapping Sessions and Optimize Coverage

  This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Identify Overlapping Sessions and Optimize Coverage states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  Coding & AlgorithmsTechnical Screen
• RobinhoodMedium·Data Scientist
  Identify Top Users with Declined Transactions in SQL

  This question evaluates proficiency in SQL data manipulation, specifically aggregation, window functions, rolling 24-hour time-window analytics, NULL handling, and conditional classification via CASE WHEN within a fraud/risk detection scenario.

  Data Manipulation (SQL/Python)Technical Screen
• RobinhoodMedium·Data Scientist
  Identify Transactions During 'Golden' Membership Period

  This question evaluates proficiency in temporal data manipulation and aggregation, covering SQL date-range joins, window functions for per-user ranking, and Python frequency counting of senders and receivers, and it falls under the Data Manipulation (SQL/Python) domain for data scientist roles.

  Data Manipulation (SQL/Python)Technical Screen
• RobinhoodMedium·Data Scientist
  List Transactions During Active 'Gold' Membership Period

  This question evaluates proficiency in SQL-based data manipulation and temporal reasoning, specifically the ability to correlate membership periods with transaction records using relational operations.

  Data Manipulation (SQL/Python)Technical Screen
• RobinhoodMedium·Data Scientist
  Write SQL and Python for transaction analytics

  This question evaluates data manipulation competency in SQL and Python, covering normalization of transaction direction, JOINs and CASE logic, window functions for ranking and aggregation, and designing single-pass counting algorithms for streaming-like inputs.

  Data Manipulation (SQL/Python)Technical Screen
• RobinhoodMedium·Data Scientist
  Write SQL to localize trading drop contributors

  This question evaluates proficiency in SQL-based data manipulation and analytics, including cohorting by signup month, daily aggregation of executed trades per active user, segmentation by platform and geolocation, and competency with joins, timestamps, and operational flags.

  Data Manipulation (SQL/Python)Technical Screen
• RobloxMedium·Data Scientist
  Analyze Recent Orders Dataset with Python/pandas

  This question evaluates proficiency in data manipulation and aggregation using Python/pandas, including extracting per-user maximums, computing overall summary statistics, and producing daily aggregates from time-stamped records.

  Data Manipulation (SQL/Python)Onsite
• RobloxHard·Data Scientist
  Apply Bayes' rule to compute posterior

  Evaluates understanding of Bayes’ rule and basic probability concepts—specifically computing a posterior probability P(A|B) and the marginal likelihood P(B) from a prior and likelihoods—in the Statistics & Math domain at a foundational-to-intermediate abstraction level.

  Statistics & MathOnline Assessment
• RobloxMedium·Data Scientist
  Choose best/worst actions under OA pressure

  This question evaluates judgment and leadership competencies in data science — including risk assessment, stakeholder impact analysis, integrity under time pressure, and handling failing tests and collaborator input — and falls under the Behavioral & Leadership category.

  Behavioral & LeadershipOnline Assessment
• RobloxMedium·Data Scientist
  Compare ROW_NUMBER, RANK, and DENSE_RANK for Top-k Results

  Compare ROW_NUMBER, RANK, and DENSE_RANK with ties, exact-row limits, distinct score levels, and deterministic top-k semantics.

  Data Manipulation (SQL/Python)Technical Screen
• RobloxEasy·Data Scientist
  Compute A/B test sample size and Bayes posterior

  This question tests the ability to calculate required sample size for a frequentist A/B test using power analysis and to perform a Bayesian update for a Bernoulli process.

  Statistics & MathOnline AssessmentStatisticsA/B TestingBayesian Inference
• RobloxMedium·Data Scientist
  Compute ARPDAU/ARPPU by country

  This question evaluates data manipulation and analytics skills for computing user- and revenue-based metrics (ARPDAU, ARPPU), focusing on aggregation, multi-key joins, deduplication, time-window filtering, and correct revenue attribution.

  Data Manipulation (SQL/Python)Technical Screen
• RobloxHard·Data Scientist
  Compute DID estimate and pretrend flag

  This Analytics & Experimentation question evaluates basic causal-inference and data-manipulation skills by requiring computation of a difference-in-differences (DID) estimate and a binary pretrend flag from panel-like arrays, at an implementation-level focused on summary statistics and edge-case handling.

  Analytics & ExperimentationOnline Assessment
• RobloxEasy·Data Scientist
  Compute diff-in-diff and pretrend flag

  This question tests the ability to calculate a difference-in-differences (DiD) estimator for causal inference and implement a basic statistical test for pre-intervention trend divergence.

  Analytics & ExperimentationOnline AssessmentCausal InferenceData WranglingStatistics
• RobloxHard·Data Scientist
  Compute minimum sample size for A/B test

  Evaluates the ability to perform sample size and power calculations for a two-sample z-test—including estimating outcome standard deviation from historical continuous data—and is categorized under Analytics & Experimentation for a Data Scientist role at an implementation-level applied statistics abstraction.

  Analytics & ExperimentationOnline Assessment
• RobloxHard·Data Scientist
  Compute sample size and Bayes posterior

  This question evaluates understanding of statistical inference and probabilistic reasoning by combining a frequentist power/sample-size computation for a two-sided two-sample z-test with a basic Bayesian conditional probability calculation.

  Statistics & MathOnline Assessment
• RobloxMedium·Data Scientist
  Defend a metric choice under scrutiny

  This question evaluates a Data Scientist's competency in metric selection, stakeholder communication, and experiment governance when defending a non-obvious primary metric.

  Behavioral & LeadershipOnsite
• RobloxHard·Data Scientist
  Demonstrate fit with quantified stories and motivations

  This question evaluates a Data Scientist's behavioral and leadership competencies, including storytelling with quantified impact, ownership of technical decisions, trade-off analysis, error detection and correction, motivation, team collaboration, and end-to-end project thinking.

  Behavioral & LeadershipTechnical Screen
• RobloxMedium·Data Scientist
  Derive variance and CTR confidence intervals

  This problem tests your understanding of statistical inference for binomial proportions, specifically calculating confidence intervals for Click-Through Rates (CTR) and understanding how to aggregate variability across multiple days.

  Statistics & MathTechnical ScreenStatisticsInferenceCTR
• RobloxMedium·Data Scientist
  Describe leading an ambiguous ads project

  This question evaluates a data scientist's end-to-end ownership, experimental and analytics skills in ads/growth contexts, including hypothesis formulation, metric and guardrail selection, trade-off reasoning, stakeholder alignment, conflict resolution, and quantifying impact.

  Behavioral & LeadershipTechnical Screen
• RobloxHard·Data Scientist
  Describe resolving revenue–UX metric conflict

  This question evaluates a data scientist's competency in metrics-driven product leadership, focusing on balancing monetization and user-experience metrics, quantitative trade-off analysis, experiment design, risk management, and cross-functional stakeholder decision-making.

  Behavioral & LeadershipTechnical Screen
• RobloxHard·Data Scientist
  Design experiment for homepage tab replacement

  This question evaluates experiment design and causal-inference competency for product changes that impact both end users and platform creators, covering randomization strategies, metric and guardrail selection, power calculations, and handling of novelty, navigation friction, and ecosystem interference.

  Analytics & ExperimentationTechnical Screen
• RobloxHard·Data Scientist
  Design leakage-free predictive maintenance pipeline

  This question evaluates a data scientist's competency in designing time-series predictive maintenance pipelines, focusing on temporal feature engineering, leakage prevention and point-in-time joins, handling late-arriving labels, class imbalance and cost-sensitive thresholding, probabilistic calibration, explainability, and operational drift monitoring. It is commonly asked in the Machine Learning domain to assess an applicant's ability to produce an end-to-end, production-ready workflow that balances practical implementation concerns with conceptual system-design reasoning, so the task is primarily practical application with important conceptual elements.

  Machine LearningOnline Assessment
• RobloxMedium·Data Scientist
  Evaluate Impact of New Roblox Homepage Tab

  Roblox data scientist experimentation prompt on evaluating a new homepage tab, including hypotheses, engagement funnel metrics, guardrails, power, duration, segmentation, cannibalization, and rollout criteria.

  Analytics & ExperimentationTechnical Screen
• RobloxEasy·Data Scientist
  Find maximum follow depth using recursion

  This question evaluates a candidate's competency with recursion, directed graph traversal, cycle detection, and memoization when computing longest-path depths in social-network-style follow graphs.

  Coding & AlgorithmsTechnical Screen
• RobloxHard·Data Scientist
  Fit logistic regression and return top features

  This question evaluates understanding of binary logistic regression, coefficient-based feature importance, and practical model-fitting considerations such as intercept inclusion and input shape handling.

  Machine LearningOnline Assessment
• RobloxMedium·Data Scientist
  Generate Friendship List with Acceptance Dates Using Pandas

  This question evaluates proficiency in data manipulation and relational reasoning using Python/pandas, focusing on transforming event logs into canonical pairwise relationships and extracting activation timestamps.

  Data Manipulation (SQL/Python)Onsite
• RobloxMedium·Data Scientist
  Implement Python Function for Statistical Test P-Values

  This question evaluates proficiency in statistical hypothesis testing, p-value interpretation, and implementing distribution-based calculations (Z and Student-t) in code, and it falls under the Coding & Algorithms domain for data scientist roles.

  Coding & AlgorithmsTechnical Screen