App Tracking Transparency

Mapendo Team
April 13, 2022
App Tracking Transparency


Apple’s release of iOS 14.5 has been a pivotal event for the app marketing ecosystem. The most relevant changes affected the attribution technology used to measure app install campaigns. Indeed, ATT forced marketers to rethink the way of running paid user acquisition campaigns. 

What is an ATT?

ATT stands for App Tracking Transparency and it has been introduced by Apple in order to preserve users’ privacy, by giving them more control over their personal data. ATT is a pop up which shows up whenever users open a new app and it asks them whether or not they want their activity and data to be tracked across mobile apps. As expected, most people choose not to give consent, opting-out ATT and, as a result, hiding their IDFA, which is the identifier for advertisers, unique for each Apple’s device. 

Why is it important?

ATT has changed the way of attributing installs and post-install events in app install campaigns because it allows users to hide their IDFA. Indeed, before iOS 14.5, IDFA was used by MMP (Mobile Measurement Partners) to match advertising activities like clicks and impressions to app installs and app events, attributing those events to the marketing campaigns responsible for them. As a result, advertisers could assess the performance of their app install campaigns and marketing partners. This attribution technology is called deterministic attribution and it is 100% accurate because IDFAs are unique for each device.

However, when users now opt-out the ATT, their IDFA is hidden to MMPs, and deterministic attribution is not possible anymore. It is possible to measure app install campaigns with deterministic attribution only when users opt-in the ATT on both the app publishers where the ad is shown and the app advertised. MMPs and marketers are left with two main alternatives in order to measure and optimize app install campaigns: probabilistic attribution and SKAdNetwork.

Probabilistic attribution uses a set of probabilities and contextual data in order to attribute installs and in-app events to media sources, while SKAdNetwork is Apple’s own attribution technology, which is 100% accurate but less effective than deterministic attribution. Indeed, postbacks are sent to marketers and MMPs with a delay of 24-48 hours, in order to clean data and respect users’èrivacy, and post-install events are not measured at a granular level, but with a 6-bit system, which makes it difficult to optimize app install campaigns in real time.

What you need to know about ATT?

  • ATT allows users to hide their IDFA and not to have their activity tracked across apps;
  • When users choose to hide their IDFA deterministic attribution is not possible;
  • In order to to make deterministic attribution possible, users must opt in in both the app publisher and the app promoted;
  • Without deterministic attribution app install campaigns are more difficult to optimize in real time.