InterviewStack.io LogoInterviewStack.io

Probability and Statistical Inference Questions

Covers fundamental probability theory and statistical inference from first principles to practical applications. Core probability concepts include sample spaces and events, independence, conditional probability, Bayes theorem, expected value, variance, and standard deviation. Reviews common probability distributions such as normal, binomial, Poisson, uniform, and exponential, their parameters, typical use cases, computation of probabilities, and approximation methods. Explains sampling distributions and the Central Limit Theorem and their implications for estimation and confidence intervals. Presents descriptive statistics and data summary measures including mean, median, variance, and standard deviation. Details the hypothesis testing workflow including null and alternative hypotheses, p values, statistical significance, type one and type two errors, power, effect size, and interpretation of results. Reviews commonly used tests and methods and guidance for selection and assumptions checking, including z tests, t tests, chi square tests, analysis of variance, and basic nonparametric alternatives. Emphasizes practical issues such as correlation versus causation, impact of sample size and data quality, assumptions validation, reasoning about rare events and tail risks, and communicating uncertainty. At more advanced levels expect experimental design and interpretation at scale including A B tests, sample size and power calculations, multiple testing and false discovery rate adjustment, and design choices for robust inference in real world systems.

HardTechnical
86 practiced
Propose a practical strategy that combines hierarchical modeling and empirical Bayes to handle multiple comparisons across many correlated metrics and experiments, with the goal of detecting important effects while controlling false discoveries. Outline the model structure, estimation approach, how to compute calibrated posterior probabilities or local FDR, and how to present results to stakeholders.
HardTechnical
59 practiced
For an observational dataset with treatment assignment and rich covariates, compare propensity score matching, inverse probability weighting (IPW), and doubly-robust estimators. State the identification assumption (strong ignorability), describe diagnostics to check overlap and balance, and discuss failure modes for each method and remedies.
HardTechnical
65 practiced
Discuss situations where the nonparametric bootstrap can fail or give misleading inference (heavy-tailed distributions, parameters at the boundary, dependent/time-series data). For each situation, describe an appropriate alternative: wild bootstrap, block bootstrap, parametric bootstrap, or subsampling, and outline when/how to apply them.
HardSystem Design
62 practiced
Design a sequential A/B testing procedure for a consumer product where stakeholders might stop early if they observe strong effects. Explain statistical approaches to control Type I error under optional stopping (alpha-spending functions, group-sequential tests, sequential probability ratio test (SPRT)), the trade-offs in power and complexity, and how you would operationalize monitoring and stopping rules in the experiment platform.
MediumTechnical
55 practiced
You observe that your training data contains several extreme outliers and heavy tails. List robust estimators for central tendency and regression (e.g., median, trimmed mean, Huber M-estimator, quantile regression). Compare their breakdown points, efficiency under Gaussian errors, and practical guidance for choosing between them.

Unlock Full Question Bank

Get access to hundreds of Probability and Statistical Inference interview questions and detailed answers.

Sign in to Continue

Join thousands of developers preparing for their dream job.