Power a test when 200 sellers are most of your GMV
Power & sample sizeMediumProblem. You want to test a seller-facing feature: a new analytics dashboard that might help sellers price better. The metric is GMV per seller. There are roughly 100,000 active sellers, but the top 200 are most of the GMV. Size the test.
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.