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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.

MediumTechnical
53 practiced
You want to measure effects of two features: Feature A (on/off) and Feature B (three levels) on user engagement. Propose a full factorial experiment and describe how to analyze results using two-way ANOVA including interaction terms. List ANOVA assumptions and practical remedies if assumptions are violated (non-normal residuals, heteroscedasticity).
HardTechnical
54 practiced
Compare classical A/B testing with multi-armed bandit (MAB) approaches for online experiments. Explain when bandits improve cumulative reward, trade-offs between exploration and confident estimation, and how to perform valid statistical inference when data collection is adaptive (e.g., reweighting or using inverse propensity scores).
MediumTechnical
100 practiced
Write Python functions that compute a 95% confidence interval for the difference between two proportions (p1 - p2) using both the Wald method and Newcombe (Wilson score) method. Explain scenarios where the Wald interval fails and why Wilson/Newcombe is preferred for rare events.
EasyTechnical
56 practiced
Explain the Central Limit Theorem (CLT) in practical terms for an AI engineer: when you estimate the mean validation loss from mini-batches, why does CLT matter and under what conditions can you apply normal-based confidence intervals to batch-level statistics? Mention sample size and finite-variance assumptions.
HardTechnical
51 practiced
Describe methods to estimate causal effects from observational data commonly used in AI: propensity score matching/weighting, regression adjustment, doubly-robust estimators, and instrumental variables. For a recommendation system where exposure is non-random, propose an identification strategy and state key assumptions required for validity.

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