Measuring Experiments

Learn how to measure experiment results using autocapture, the manual tracking API, and Sidecar callbacks for analytics integrations.

Using Autocapture

Sidecar automatically tracks various web activities, letting you create simple and complex metrics in the Statsig console without writing code. Create a new metric in the Metrics tab on the Statsig console to get started. For a full list of automatically logged metrics, refer to Autocapture on the Web.

Using the tracking API

You can track events manually for actions not captured by Autocapture. To track events to Statsig, call StatsigSidecar.logEvent, which accepts the same arguments as the Statsig JS SDK as documented in Logging an event. You can call this method before the init routine completes.

// example order event
StatsigSidecar.logEvent('Order', null, {
  total: 54.66,
  units: 3,
  unitAvgCost: 18.22
});

Per-assignment callback for outbound integrations

You can bind a callback that is invoked each time Sidecar activates an experiment assignment, including experiments activated later by prerun scripts.

This method must be defined before the Sidecar client script.

window.statsigSidecarConfig = {
  onExperimentEvaluation: function (event) {
    /**
     * add your own callback routine here
     * ie; annotating 3rd party analytics tools with assignment info
     */
    window.dataLayer = window.dataLayer || [];
    window.dataLayer.push({
      event: "statsig_experiment_evaluation",
      experiment_name: event.experimentName,
      experiment_group_name: event.groupName,
    });
  }
}

The callback payload includes:

event.name - always "experiment_evaluation"
event.experiment - the full Statsig experiment object
event.experimentName - the Sidecar experiment name, or the Statsig experiment name as a fallback
event.groupName - the assigned group / variant, or null if unavailable

Post-experiment callback for one-time readiness hooks

You can bind window.postExperimentCallback to receive a callback after Sidecar finishes its initial run. This callback fires even when there are no experiments, but doesn't cover experiments activated later by prerun scripts.

window.postExperimentCallback = function(statsigClient, experimentIds) {
  // One-time initialization hook after Sidecar finishes the initial run
}

Disabling all logging

To disable all logging to Statsig (both autocapture events and experiment exposure logging), append the following query string parameter to the Sidecar script URL: &autostart=0. This is useful for GDPR compliance. You can re-enable events later with client.updateRuntimeOptions({disableLogging: false}).

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