For some experiments, assignment and exposure are separate events (e.g. you may need to generate a web page that has an experiment at the bottom of the page. Users are exposed only if the user scrolls down and sees the experiment). When using Statsig SDKs you can use getExperimentWithExposureLoggingDisabled
on assignment and manuallyLogExperimentExposure
at the point of exposure.
If you are using a 3rd party SDK, you can filter exposures based on a Qualifying Event. You can choose to filter assignments to only include subjects that have either generated (or not generated) a qualifying event - within a time window.
You can find these settings in the Advanced options of the Setup page when creating an Analyze-only Experiment.