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A metric describes an aggregation of user activity, reflected in product telemetry or another data source, to a scalar value per user.

For example, "sum of a user's active hours" is a metric. So is "a user's average page load time."

Metrics are applied over a window of time, called an analysis window. The Jetstream overview has more details about analysis windows.

What's in a name?

Glean also has a concept called metrics; ours are different.

Jetstream metrics represent aggregations of the recorded values of Glean metrics.

Statistics summarize the distribution of metrics within and between branches of an experiment.

How do I add a metric to my experiment?#

You can add a metric to your experiment by having a data scientist write a custom configuration for your experiment, or by associating an Outcome with your experiment in the Experiment Console.

Outcomes are collections of metrics that relate to each other. Data scientists can extend and define outcomes in the outcomes path of the jetstream-config repository.

A small set of guardrail metrics (called Core Firefox Metrics in Nimbus Console) specific to each platform is run by default for each experiment. These are defined in the Jetstream-config repository in jetstream-config/defaults/