What are impressions and decisions in Feature Experimentation

Optimizely Experimentation records an impression when a user is exposed to a flag variation. Specifically, Optimizely logs an impression through the following sequence:

Impressions generate the visitor counts on the Experimentation ResultsExperimentation Results page and serve as the denominator for measuring conversion rates.

You can use the decide methods to return a flag decision for a user. The flag decision includes the flag-enabled or disabled status and the flag variation.

A decision event is an SDK action that triggers a network request. To avoid the request, you can disable dispatching decision events for the decide method using the SDK's event dispatcher.

For information, see the following Feature Experimentation's SDK decide method documentation:

See the event dispatcher documentation for the Feature Experimentation SDK for information on managing network requests:

When the user is bucketed into an A/B testA/B test, regardless of whether the flag is enabled or disabled in the variation.

Optimizely logs the impression after receiving the decision event, indicating the user was bucketed into the experiment.

Examples:

Depending on your application logic, your users may trigger rapid bursts of impressions. To avoid overcounting these bursts on your Experimentation Results pageExperimentation Results page, Optimizely uses fixed-interval impressions deduplication. All impressions received within fixed 5-second intervals count as one impression for each user in an experiment. Optimizely Experimentation buckets events into the fixed time windows based on when Optimizely Experimentation receives the event.

See Impression in Optimizely ExperimentationImpression in Optimizely Experimentation.