What is a north star metric and proxy metrics?

North Star Metric (NSM) is a key indicator that reflects the core value of a product for users and is directly related to business growth. It is a metric that teams focus on to measure the long-term success of the product.

For example, for a streaming service, NSM could be "video watch time per month" — the more users watch, the better the product performs its function.

Proxy Metrics are auxiliary metrics that are indirectly related to the North Star Metric and are used for more immediate monitoring and experiments. They help understand how changes affect NSM, especially when NSM is measured with a delay or is hard to measure directly.

Example:

• NSM: number of active users per month
• Proxy Metrics: number of registrations per day, number of sessions per day

In A/B tests, proxy metrics allow for faster assessment of the impact of changes before the main metric data appears.