A/B Testing Errors and Estimation Under Skewed Metrics
Context
You are analyzing an A/B experiment for a product feature. You need to explain the statistical error types and defend thresholds you would use. The primary metric can be heavy-tailed (e.g., time spent, revenue per user) with outliers.
Tasks
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Define and contrast Type I and Type II errors in A/B testing, and explain how you would choose acceptable levels (α and β/power) in this context.
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If the metric distribution is highly skewed with outliers, describe how you would estimate the treatment lift and construct a confidence interval. Discuss appropriate methods (e.g., non-parametric tests, bootstrapping, or transformations) and when you would use them.