Data Scientist Interview Questions

Showing 1531–1560 of 1971 results

• RobloxEasy·Data Scientist
  Implement four DS coding tasks

  This multi-part question evaluates a data scientist's competencies in statistical inference (sample size and z-test calculations), causal inference and parallel-trends validation (difference-in-differences), Bayesian probability updating, and interpretable supervised learning feature importance, all framed as coding tasks.

  Coding & AlgorithmsOnline Assessment
• RobloxHard·Data Scientist
  Implement robust one/two-sided p-value function

  This question evaluates proficiency in statistical hypothesis testing, numerical computing, and numerical stability when implementing p-value calculations for z and t distributions, and it targets the Statistics & Math domain for a data scientist role.

  Statistics & MathTechnical Screen
• RobloxMedium·Data Scientist
  Implement streaming CTR with deduplication

  This question evaluates streaming data-processing and algorithmic design skills, specifically time-windowed aggregation, click deduplication, late-event handling, state management, and selection of data structures for per-campaign CTR computation.

  Coding & AlgorithmsTechnical Screen
• RobloxMedium·Data Scientist
  Match requests and accepts into friendships in SQL

  This question evaluates a candidate's competency in SQL data manipulation, focusing on temporal joins, deduplication of bidirectional relationships, selecting the earliest valid event, and reasoning about event-order constraints.

  Data Manipulation (SQL/Python)Onsite
• RobloxMedium·Data Scientist
  Measure Success for a New Chat System

  Build a chat-system launch framework with meaningful communication metrics, reliability and safety guardrails, and experiments that address network effects.

  Analytics & ExperimentationTechnical Screen
• RobloxMedium·Data Scientist
  Optimize assembly-line scheduling with changeovers

  This question evaluates combinatorial optimization and scheduling competencies, specifically reasoning about NP-hardness, sequence-dependent setup times, precedence and downtime constraints, and designing exact and heuristic solvers for makespan minimization.

  Coding & AlgorithmsOnline Assessment
• RobloxMedium·Data Scientist
  Optimize bread-factory pipeline for max profit

  This question evaluates skills in combinatorial optimization, budgeted resource allocation, bottleneck throughput modeling, and algorithm design with cost amortization for maximizing profit under constraints.

  Coding & AlgorithmsOnsite
• RobloxMedium·Data Scientist
  Write SQL for ads metrics and variability

  This question evaluates a candidate's ability to perform SQL-based data manipulation and analytics, including deduplication of events, computation of daily and campaign-level metrics (CTR, CPC), and calculation of statistical summaries (mean and standard deviation) and outlier detection over a specified date range.

  Data Manipulation (SQL/Python)Technical Screen
• RobloxEasy·Data Scientist
  Write SQL for influence score and follower growth

  This question evaluates SQL data manipulation competencies such as joins, aggregations, distinct counts, window functions, and time-based grouping for computing an influence score (engagements on a user's posts plus follower count) and monthly follower growth, and it falls under Data Manipulation (SQL/Python).

  Data Manipulation (SQL/Python)Technical Screen
• RobloxMedium·Data Scientist
  Write SQL to flag suspect payments and chargebacks

  This question evaluates proficiency with SQL conditional logic (CASE WHEN), JOINs, date/time arithmetic, aggregation, and encoding business rules for flagging suspect payments and chargebacks, and is categorized under Data Manipulation (SQL/Python) for a Data Scientist role.

  Data Manipulation (SQL/Python)HR Screen
• RCRokos Capital ManagementMedium·Data Scientist
  Explain motivations and background for hedge fund role

  This question evaluates a data scientist's background, motivation for working in a hedge fund, verbal communication and storytelling skills, and evidence of domain-relevant achievements from academics and internships.

  Behavioral & LeadershipHR Screen
• RRokuEasy·Data Scientist
  Explain Bias-Variance Trade-off Simply for Stakeholders

  Evaluates the ability to explain the bias-variance trade-off to non-technical stakeholders. Strong answers define bias as underfitting, variance as overfitting, use a clear analogy, and explain why models must generalize to new data rather than memorize training data.

  Statistics & MathTechnical Screen
• RRokuMedium·Data Scientist
  Explain and quantify bias-variance tradeoff

  This question tests the conceptual understanding of the bias-variance decomposition of mean squared error and how specific modeling choices influence these components.

  Machine LearningTechnical ScreenBias-VarianceModel EvaluationSupervised Learning
• RRokuMedium·Data Scientist
  Measure Speaker's Impact Using Propensity Score Matching

  Evaluates causal inference for optional smart speaker ownership using propensity score matching and staggered adoption. Strong answers address self-selection, construct matched or weighted controls, validate balance and pre-trends, estimate ATT, and run placebo and sensitivity analyses.

  Analytics & ExperimentationTechnical Screen
• RRokuMedium·Data Scientist
  Write SQL for profit, growth, retention

  This question evaluates a candidate's ability to perform advanced SQL data manipulation — specifically rolling-window aggregations, revenue and gross profit computations that account for refunds, order status and test flags, plus cohort retention and week-over-week growth analysis.

  Data Manipulation (SQL/Python)Technical Screen
• SIG (Susquehanna)Medium·Data Scientist
  Analyze Knights-and-Knaves Dialogue Variants

  Analyze Knights-and-Knaves Dialogue Variants 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
• SIG (Susquehanna)Easy·Data Scientist
  Calculate Expected Payoff from Two Dice

  This problem tests fundamental knowledge of probability, expected value, and partitioning sample spaces to calculate the average outcome of a stochastic process.

  Statistics & MathOnline AssessmentProbabilityExpected ValueStatistics
• SIG (Susquehanna)Easy·Data Scientist
  Compute Conditional Age Probability Among Cyclists

  This question tests the ability to interpret a contingency table and calculate conditional probabilities by narrowing the sample space to a specific sub-group.

  Statistics & MathOnline AssessmentProbabilityStatisticsContingency Tables
• SIG (Susquehanna)Hard·Data Scientist
  Compute answers to probability and counting puzzles

  This problem tests your ability to model sequential probabilistic events using combinatorics and conditional probability, specifically requiring the calculation of expected outcomes in a game of chance.

  Statistics & MathTechnical ScreenProbabilityExpectationCombinatorics
• SIG (Susquehanna)Medium·Data Scientist
  Compute bus-on-time and dice-sum probabilities

  This problem tests your ability to calculate probabilities involving continuous uniform distributions and discrete combinations of independent events.

  Coding & AlgorithmsHR ScreenProbabilityCombinatoricsUniform Distribution
• SIG (Susquehanna)Medium·Data Scientist
  Compute ruin probability with bold betting

  This question evaluates understanding of probability theory and stochastic processes, focusing on ruin probabilities under a bold betting strategy with state-dependent wagers.

  Statistics & MathOnline Assessment
• SIG (Susquehanna)Easy·Data Scientist
  Compute stockout sufficiency probability

  This question evaluates understanding of discrete probability and binomial models for independent Bernoulli trials, testing the ability to compute the probability that a limited resource meets random demand.

  Statistics & MathOnline Assessment
• SIG (Susquehanna)Easy·Data Scientist
  Compute the Probability Two Bloom Intervals Overlap

  Calculate the probability that two independent events with different known durations overlap within a fixed time window using geometric probability.

  Statistics & MathOnline AssessmentProbabilityContinuous DistributionsGeometric Probability
• SIG (Susquehanna)Easy·Data Scientist
  Condition on a Chosen Rabbit Losing

  Calculate the conditional probability that a randomly selected rabbit is the least athletic of three rabbits given that it lost its benchmark race, using Bayes' theorem.

  Statistics & MathOnline AssessmentProbabilityBayes' TheoremConditional Probability
• SIG (Susquehanna)Easy·Data Scientist
  Count Cookie Flavor Combinations

  Calculate the number of distinct unordered combinations when selecting 5 cookies from 4 available flavors with replacement, and contrast this with the ordered outcome space.

  Statistics & MathOnline Assessmentcombinatoricsstars-and-barsprobability
• SIG (Susquehanna)Easy·Data Scientist
  Count Grid Paths with No Three Equal Moves

  Count lattice paths from `(0, 0)` to `(5, 5)` that never use three identical directions consecutively. The solution converts paths into alternating runs of length one or two, counts bounded compositions for equal and unequal run totals, and derives 84 valid paths.

  Statistics & MathOnline Assessment
• SIG (Susquehanna)Easy·Data Scientist
  Deduce Cat Counts from Conditional Truth Rules

  Deduce the exact number of cats owned by three individuals based on conditional truth-telling rules, percentage relations, and average constraints.

  Statistics & MathOnline AssessmentLogic PuzzleNumber TheoryIntegrality
• SIG (Susquehanna)Easy·Data Scientist
  Determine a Canoe Departure Time

  This problem tests algebraic modeling and systems of linear equations by requiring the candidate to derive the counts of different entities based on a total sum constraint.

  Statistics & MathOnline AssessmentAlgebraLinear EquationsLogic
• SIG (Susquehanna)Medium·Data Scientist
  Determine departure time from travel times

  This question evaluates a candidate's understanding of relative motion, time-distance-rate relationships, algebraic modeling, and quantitative reasoning. Commonly asked in technical interviews for Statistics & Math and Data Scientist roles, it assesses the practical application of setting up and manipulating equations from multi-step word problems rather than purely conceptual theory.

  Statistics & MathOnline Assessment
• SIG (Susquehanna)Easy·Data Scientist
  Determine knights and knaves roles

  This interview question evaluates statistical assumptions, formulas, estimation strategy, uncertainty, edge cases, and interpretation in a realistic interview setting. A strong answer for Determine knights and knaves roles states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  Statistics & MathTechnical Screen