No A/B for a city-level campaign — synthetic control
Causal inferenceHardProblem. A campaign or product change launched in one city and you can't A/B it. How do you estimate its causal effect with synthetic control?
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.