Your order-rate experiment is underpowered — how do you fix it?
Variance & ratio metricsMediumProblem. An experiment on order rate can't reach significance in a reasonable time — the metric is too noisy. How do you get power without just waiting for a huge sample?
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.