Root-Causing a Fall in Instagram's Monthly User Retention

You are a product manager for Instagram, and month-over-month retention has dropped by 20%. Walk through what might be causing the drop and how you would narrow down the cause. ```hint Pin down the metric, then localize Settle what the 20% measures and whether the data can be trusted, then find which users and which time window carry the drop before naming causes. ``` ### Clarifying Questions - Is the 20% a relative decline (for example, retention moving from 50% to 40%) or a fall of 20 percentage points? - Which retention is this: users active last month who came back this month, or new sign-ups returning in their second month? Does "active" mean opening the app or a meaningful action such as viewing or posting? - Did the drop appear within one month or build over several, and is it visible on every platform and in every region? ### What a Strong Answer Covers - Clarifying the metric definition, the size and the timing of the drop before diagnosing - Ruling out tracking, definition and calendar artifacts first - Segmenting by cohort, platform, region, user type and surface to localize the decline - Separating internal from external causes and ordering hypotheses with the evidence that would confirm each - A response plan once the cause is found ### Follow-up Questions - If the drop turns out to sit entirely in new users' second month, which hypotheses move to the top, and what would you check next? - How would you test whether a competitor's launch caused the drop when you cannot see the competitor's data? - Once you know the cause, what recovery target and guardrail metrics would you set?