You can't A/B a marketing channel — measure its incrementality
Causal inferenceHardProblem. You want the true incremental orders from a paid marketing channel (e.g., a TV or paid-social campaign) that you can't user-randomize. How do you measure 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.