The release of Apple iOS14.5 introduced a requirement to obtain an official opt-in from app users to track them across apps and websites owned by other companies, referred to as ATT (App Tracking Transparency). The ATT opt-in rate refers to the percentage of users who select the “Allow” option when they are presented with the ATT prompt in an app.
When exploring ATT opt-in rates, it’s important to understand how the rate is defined, as multiple definitions have been observed in the market.
Every app user can be one of these five states:
- Prompted, opted in
- Prompted, opted out
- Not yet prompted
- Restricted from being prompted due to Limit Ad Tracking setting or other criteria specified by Apple, such as age or the device’s controlling organization.
- Opted out device-wide (This is reported to apps the same way as state 2)
The most common definition of ATT opt-in rate is 1/(1+2+5), as defined above, which determines how effective the ATT prompt is at securing explicit permission.
The other definition seen in the market is 1/(1+2+3+4), which reflects the total percentage of an app’s user base that has shared identifiable data with the app developer.