Use the action’s click-through-ratio (CTR) to know an action's effectiveness. It will help you enhance the user experience by removing actions that users do not value and adding more effective actions.
Tap on an action or use the gear to expand it to see a snapshot metrics over the past 30 days. A line graph shows the impressions and click-throughs (i.e. taps) for that action.
An Impression is measured when an action is displayed on a page. Because pages are dynamic, impressions are different than scans (i.e. page views) because some Actions are scheduled, and others are added or removed during the measurement period.
A Tap is measured when an Action is clicked. It is a measure of true engagement.
A "Click-Through-Ratio" (CTR) is especially important for users who update content often.
If an Action was added halfway through a reporting period, it will have fewer impression than one there the whole time. If both have the same number of taps, then the one there half the time performed better and will have a higher CTR.
Metrics are for a specific App ID/Action combination, so even if an Action is used on several different pages, it will have different metrics for each page it is used on. This will allow you to see if Actions are more effective when used on different Pages.