Define Metrics and Experiment Guardrails for a New Consumer Feature

Context (Assumption to Ground the Exercise)

Assume you are launching a "Price Drop Alerts" feature in a consumer travel/marketplace app. Users can follow a listing or search and receive push/email alerts when the price drops or when an excellent deal appears.

Task

1. Propose a single North Star Metric (NSM) for this feature.
2. Define 5–8 input (driver) metrics that ladder up to the NSM.
3. Define guardrail metrics (user experience, quality, marketplace health, operational risk).
4. Describe how you would instrument events and attributes to compute these metrics accurately.
5. Explain how to avoid metric gaming and perverse incentives.
6. Explain how you would set baselines and targets for these metrics.