Metrics question

You are the Facebook PM responsible for birthday notifications. How would you measure success?

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Whether the candidate can define success for a low-frequency, emotionally-driven feature rather than judging it by raw engagement volume alone.

Clarify the goal: birthday notifications aim to prompt low-effort but meaningful social interactions (wishes, gifts) that strengthen relationships and bring users back to the app.
Define adoption: percent of birthdays where at least one friend receives and acts on a notification.
Define engagement: percent of notified users who post a wish, comment, or send a gift, and time spent on the birthday person's profile that day.
Add a downstream metric: whether the birthday person's own engagement (return visits, posts) increases that week versus a typical week.
Set a guardrail: notification fatigue or opt-out rate, since birthday reminders are a frequent, potentially annoying notification type.

Frames the feature's value as strengthening relationships and driving reciprocal engagement, not raw notification click-through alone.
Includes the birthday person's own return-visit lift as a downstream success signal, capturing the emotional payoff of the feature.
Adds notification fatigue as a guardrail, since this is a recurring, easy-to-mute notification type.

Measuring only notification click-through rate without checking downstream engagement or fatigue.
Ignoring the birthday person's own experience and focusing only on the notified friends.

How would you personalize notification timing to reduce fatigue while maximizing wishes sent?
What would you do if opt-out rate for birthday notifications starts climbing?