The buffering blackout

A root cause analysis question from a product manager interview, set at Loopr, a fictional short-video / creator platform company.

The question

Skills this case tests

A starting metric tree

Watch time per DAU = sessions per DAU × videos played per session × seconds watched per video

How to approach this case

Confirm the metric (foreground minutes ÷ daily active users), whether the drop was sudden, and whether it's real: compare client-side minutes with an independent source such as server delivery logs. Then split numerator from denominator. If there are as many users as before, break time per user into sessions, videos per session and time per video to find where it leaks. For a short-video app, look at playback quality as well as recommendations. Segment by platform, device capability, city tier, network type and hour of day, and line the pattern up with anything shipped to some users but not others. A strong close gives an immediate mitigation, a proper fix, a release guardrail to stop it happening again, and the trade-off you're accepting.

The full method for root cause analysis questions · A worked example answer

After the mock interview you get scores on five skills, what to fix with quotes from your answers, and the ideal path for this case.