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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 421–450 of 1076 results

  • GoogleMediumData Scientist
    Describe Your Research and Cross-Functional Collaboration Experience

    Evaluates behavioral storytelling for research rigor and cross-functional collaboration in data science. Strong answers explain problem framing, methodology, validation, stakeholder alignment, impact, and limitations.

    Behavioral & LeadershipTechnical Screen
  • GoogleMediumData Scientist
    Design A/B Test to Isolate Product Usage Drop Causes

    Evaluates experimentation strategy for diagnosing a simultaneous product usage drop in the U.S. and Mexico. Strong answers identify confounders, design tests or quasi-experiments, control variables, and report causal lift.

    Analytics & ExperimentationTechnical Screen
  • GoogleMediumData Scientist
    Design Scalable Database and Analyze E-commerce Data

    This question evaluates relational database design and data-manipulation competencies, including schema modeling and normalization, SQL-based association analysis for co-purchases, and vectorized data transformation using Python/Pandas.

    Data Manipulation (SQL/Python)Technical Screen
  • GoogleMediumData Scientist
    Design a scalable video platform database

    This question evaluates relational database design and data engineering competencies—including schema modeling, many-to-many relationships, idempotent ingest, indexing and partitioning, OLTP versus analytics integration, GDPR-compliant deletion strategies, and query formulation—within the Data Manipulation (SQL/Python) domain for a Data Scientist role. It is commonly asked to assess both conceptual understanding and practical application of scalable data architectures, performance tuning, and compliance trade-offs, focusing on the ability to reason about schema choices, read/write optimization, and analytics integration without implementation details.

    Data Manipulation (SQL/Python)Technical Screen
  • GoogleHardData Scientist
    Design an Unbiased Upgrade Experiment

    This question tests the ability to design an A/B test for a software upgrade, specifically focusing on handling non-compliance, selection bias, and the identification of causal effects in a real-world product environment.

    Analytics & ExperimentationTechnical ScreenCausal InferenceExperiment DesignA/B Testing
  • GoogleMediumData Scientist
    Determine Impact of New Chat-Notification on User Engagement

    Determine Impact of New Chat-Notification on User Engagement 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
  • GoogleEasyData Scientist
    Determine Normality of Single Observation with Z-Test

    Evaluates hypothesis testing for a single observation against a fully specified standard normal distribution. Strong answers state hypotheses, use z = x, define critical values and p-values, and note limitations.

    Statistics & MathTechnical Screen
  • GoogleHardData Scientist
    Diagnose Google Meet Disconnections and Assess Business Impact

    Evaluates reliability analytics for Google Meet disconnections and enterprise renewal impact. Strong answers define call drops, use client and server logs to localize root causes, estimate account-level retention impact, and prioritize fixes using quantified business risk.

    Analytics & ExperimentationTechnical Screen
  • GoogleHardData Scientist
    Diagnose and fix flawed model fit

    This question tests your ability to diagnose poor model performance in a binary classification task involving imbalanced data, high-cardinality categorical features, and potential bias.

    Machine LearningTechnical ScreenClassificationImbalanced DataFeature Engineering
  • GoogleMediumData Scientist
    Estimate percentile from buckets

    Estimate a percentile from histogram buckets by locating the cumulative-count bucket, explaining why midpoint can be poor, interpolating within the bucket under explicit assumptions, handling log-spaced buckets and edge cases, and reporting uncertainty when buckets are coarse.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Estimate population singletons from a 10% log

    This question evaluates mastery of statistical estimation and sampling theory, including recognition of bias from subsampling, frequency‑of‑frequencies modeling for rare events, uncertainty quantification under heavy‑tailed counts, and design of simulation studies.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Estimate unbiased ad scores with many reviewers

    This problem tests the ability to design an estimation framework that accounts for rater bias and variance, specifically applying concepts like hierarchical modeling or fixed-effect normalization to estimate latent variables.

    Statistics & MathTechnical ScreenStatisticsModelingBias
  • GoogleHardData Scientist
    Evaluate AI Workflow Product Metrics

    Design an end-to-end measurement and experimentation framework for a generative AI workflow-suggestion tool. Tests metric taxonomy, funnel analytics, instrumentation pitfalls, and causal inference under interference.

    Analytics & ExperimentationTechnical Screenexperimentationproduct-metricscausal-inference
  • GoogleMediumData Scientist
    Evaluate Auto-Reply Feature Success with Metrics and Experiments

    Evaluates metrics and experimentation for an auto-reply suggestion feature in chat. Strong answers define adoption, latency, conversation quality, retention, and safety guardrails, design a causal experiment, and diagnose inconclusive results through funnel, segment, quality, and UI analyses.

    Analytics & ExperimentationTechnical Screen
  • GoogleMediumData Scientist
    Evaluate Optimal Jogging Routes Feature with A/B Testing

    Evaluates A/B test design for Google Maps jogging route recommendations. Strong answers define jogging intent and exposure, measure completed runs and satisfaction, include safety and privacy guardrails, and specify randomization, MDE, power, logging, and rollout criteria.

    Analytics & ExperimentationTechnical Screen
  • GoogleHardData Scientist
    Experimentally evaluate jogging-route recommendations

    This question evaluates competency in experimental design, metric selection and definition, statistical power/MDE calculation, contamination prevention, and operational monitoring for route recommendation features, targeted at Analytics & Experimentation for a Data Scientist role.

    Analytics & ExperimentationTechnical Screen
  • GoogleHardData Scientist
    Explain Bootstrap and Prove Uniformity

    This question tests the conceptual understanding of bootstrap resampling for variance estimation and the mathematical proof of probability distributions using the properties of the Uniform distribution.

    Statistics & MathTechnical ScreenStatisticsProbabilityBootstrap
  • GoogleHardData Scientist
    Explain Bootstrap and Statistical Inference

    This problem tests your understanding of bootstrap resampling theory, confidence interval construction, and the statistical trade-offs involved in hypothesis testing for small-sample experiments.

    Statistics & MathTechnical ScreenBootstrapHypothesis TestingMLE
  • GoogleMediumData Scientist
    Explain Simpson’s Paradox and Its Causes with Example

    Evaluates Simpson's paradox through definition, confounding, subgroup imbalance, and a numeric reversal example. Strong answers compare stratified and aggregate rates and explain when each comparison matters.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Explain and resolve Simpson’s paradox

    This question evaluates understanding of Simpson's paradox, confounding, and causal reasoning, checking numerical interpretation of subgroup versus aggregate statistics and the ability to recognize when aggregated averages can mislead.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Explain linear regression to non‑technical stakeholders

    This question assesses the ability to communicate complex statistical models to non-technical stakeholders, focusing on clarity, intuition, and identifying limitations.

    Machine LearningTechnical ScreenCommunicationLinear RegressionStatistics
  • GoogleMediumData Scientist
    Generate Samples from Truncated Normal Distribution

    Evaluates truncated normal distribution fundamentals and sampling methods for lower-tail truncation. Strong answers name the lower-truncated normal, provide the PDF and CDF, and compare inverse-CDF, rejection, and tail-efficient samplers.

    Statistics & MathTechnical Screen
  • GoogleMediumData Scientist
    Generate Uniform Samples and Estimate Percentiles

    This problem tests the ability to generate uniform spatial samples using standard random functions and the mathematical application of linear interpolation for percentile estimation from binned data.

    Statistics & MathTechnical ScreenProbabilityStatisticsInterpolation
  • GoogleMediumData Scientist
    Identify and Fix Predictive Model Performance Gaps

    Evaluates predictive-model audit skills across month encoding, feature scaling, and imbalanced classification. Strong answers fix cyclical seasonality, standardize where needed, and adjust losses or thresholds for recall.

    Machine LearningTechnical Screen
  • GoogleMediumData Scientist
    Implement Sampling and Minimize Loss in Numerical Coding

    This question evaluates proficiency in probability and numerical methods, focusing on sampling from truncated distributions and analytical properties of estimators under various loss functions.

    Coding & AlgorithmsTechnical Screen
  • GoogleMediumData Scientist
    Implement anagram check and stable deduplication

    This question evaluates streaming algorithm design, Unicode normalization and locale-aware text processing, multiset frequency counting under tight time and memory bounds for an anagram checker, and stable, order-preserving deduplication with custom keys and NaN handling; it is in the Coding & Algorithms domain for a Data Scientist position.

    Coding & AlgorithmsTechnical Screen
  • GoogleMediumData Scientist
    Implement percentage RMSE and bootstrap its CI

    This question evaluates implementation and statistical reasoning skills, focusing on robust numerical computation of percentage RMSE (including handling zeros/negatives, optional country weights, and numerical stability) and nonparametric bootstrap methods for confidence intervals.

    Coding & AlgorithmsTechnical Screen
  • GoogleMediumData Scientist
    Implement piecewise linear interpolation for time-to-empty

    This question evaluates numerical interpolation, time-series data cleaning, monotonicity preservation, extrapolation, and numerical stability skills applied to battery discharge curves, and falls under coding and algorithms within a data science domain.

    Coding & AlgorithmsTechnical Screen
  • GoogleMediumData Scientist
    Implement sampling and subarray scan

    This question evaluates probabilistic sampling and random-number transformation concepts for generating uniform points in a continuous domain, alongside array-processing and algorithmic analysis skills for identifying the longest strictly increasing contiguous subarray.

    Coding & AlgorithmsTechnical Screen
  • GoogleEasyData Scientist
    Implement sampling, subarray scan, and percentile estimate

    This problem tests your ability to generate random uniform points within a geometric shape, process contiguous array properties using linear scans, and perform linear interpolation on histogram data to approximate percentiles.

    Coding & AlgorithmsTechnical ScreenGeometryAlgorithmsStatistics