Adoption is opt-in. Randomize the invitation and estimate the effect.
Causal inferenceHardProblem. A Dashboard feature suggests checkout changes to businesses, and they decide whether to switch it on. Comparing adopters with non-adopters is biased, because fast-growing businesses opt in more. You can't force businesses to use it. How would you design a study that gives a causal estimate, and how would you analyze it?
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.