Investigate a 10% DAU Drop in Yahoo Mail
Scenario
Yahoo Mail suddenly reports a 10% decline in daily active users (DAU).
Task
Walk through how you would investigate and diagnose the root cause of this 10% DAU drop. Specify:
-
What data you would pull.
-
Which funnels or cohorts you would examine.
-
How you would rule out internal versus external factors.
Hints
-
Form a hypothesis tree.
-
Segment traffic by platform (web, iOS, Android), geography, and user cohorts (new vs. returning, tenure).
-
Inspect release logs, outages/incidents, A/B experiments, feature flags.
-
Check marketing changes, seasonality/day-of-week/holidays, and competitor or ecosystem news.
Minimal context/assumptions
-
DAU = count of unique accounts with at least one qualifying session or key event (e.g., inbox_view, email_read, compose_send) in a calendar day.
-
Yahoo Mail traffic spans web and mobile apps; notifications/push and email delivery ecosystem can affect engagement.