Derive the estimator that makes a biased sample unbiased
Variance & ratio metricsHardProblem. You deliberately oversampled high-exposure, high-risk content. A colleague computes prevalence as the fraction of sampled items that were labeled violating and gets 0.8%, when the true platform rate is nearer 0.08%. Explain what went wrong, derive the correct estimator, and give it a confidence interval.
Before you reveal: say your answer out loud, as if you were in the real interview — get your reasoning across clearly first. There is no single correct answer: reading what the interviewer is really after and defending your own thinking is what makes an answer strong.