Skip to main content

Metrics

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?​

A small set of default, critical guardrail metrics that are specific to each platform are run by default for each experiment. Sometimes also called Core metrics. These are defined for each platform in the metric-hub repository in jetstream/defaults/. Look at the file for your platform. At the top you will see the metrics collected and the timeframe they are available: daily, weekly, or overall (at the end of the experiment). For help understanding any aspect of guardrail metrics on your platform - link to the file and ask in #ask-experimenter.

Pre-defined Metrics, AKA Outcomes are collections of metrics that relate to each other. You must associate these pre-defined metrics (outcomes) with your experiment BEFORE LAUNCH in the Experiment Console - Metrics section. Data scientists can extend and defined outcomes in the outcomes path of the metric-hub repository. See what Outcomes are available.

If the metrics you need are not covered by Default (guardrail) or existing Pre-defined Outcomes - you can add a custom metric to your experiment by working with a data scientist to write a custom configuration for your experiment.

What are the default guardrail metrics?​

Open the file for your platform to see the most recent list of what is included. These don’t change often, but they can.

The guardrail metrics for Desktop as of June 2025.

KPI

  • "retained",
  • "Days_of_use", Engagement and KPI
  • "active_hours",
  • "Qualified_cumulative_days_of_use",
  • "Client_level_daily_active_users_v2",
  • "uri_count"

Search Related

  • "Ad_clicks",
  • "Organic_search_count",
  • "search_count",
  • "searches_with_ads",
  • "tagged_search_count",
  • "tagged_follow_on_search_count",
  • "Uri_count"

Leading indicators. KPI's are hard to move, but these are known positive leading indicators that can impacted KPI metrics.

  • "Is_default_browser",

The guardrail metrics for Android as of June 2025.

KPI metrics:

  • "retained",
  • "days_of_use",

Engagement with browser metrics:

  • "Active_hours"
  • "Total_uri_count",
  • "Client_level_daily_active_users_v2",

Search related metrics:

  • "Serp_ad_clicks",
  • "Organic_searches",
  • "Search_count",
  • "Searches_with_ads",
  • "Tagged_follow_on_searches",

The guardrail metrics for iOS as of June 2025.

KPI

  • "Days_of_use",
  • "retained",

Engagement

  • "Active_hours",
  • "client_level_daily_active_users_v2",

Search Related

  • "search_count",
  • "serp_ad_clicks",