# Define a north-star metric

> Pick a product. Define its north-star metric (one number that captures customer value), 2-3 input metrics that drive it, and a guardrail metric you must not regress.

Canonical: https://learn.significanthobbies.com/curriculum/drills/define-north-star-metric

Pick a product. Define its north-star metric (one number that captures customer value), 2-3 input metrics that drive it, and a guardrail metric you must not regress.

## The mechanism

Good analytics looks like a small tree: one north-star metric that captures the value users get, two or three input metrics that drive it, and one guardrail you must not regress on. If a PM cannot make a tradeoff from this tree alone, the tree is wrong.

## Expected evidence

A tree: north-star → inputs → guardrail, each with a one-sentence rationale.

## Hints

- North-star is not revenue. It is the value the user gets.
- A good guardrail is something you would never trade away.

## Sources and practice

- [PostHog — Product analytics docs](https://posthog.com/docs/product-analytics)
- [Study Product Analytics](https://learn.significanthobbies.com/curriculum/concepts/product-analytics)
- [Try the interactive drill](https://learn.significanthobbies.com/drills/define-north-star-metric)
- [All practice briefs](https://learn.significanthobbies.com/curriculum/drills/)