Do friends cause retention, or do retained users add friends?

Causal inferenceHard

Problem. Users with more friends retain much better. Leadership concludes "add more friends → more retention" and wants to push connections hard. Why be skeptical, and how would you estimate the true causal effect of a connection?

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.

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