Online to Offline Advertising, also known as Omnichannel, relates to online advertising driving conversions in store, typically local stores. This use case is enabled with Store attribution, which attributes typically a in-store purchase to an online advertising campaign. Currently, such attribution relies on the user's email address obtained from their loyalty program (if they are a member) to link an offline purchase to an online identifier through the same hashed email address.

However, the Attribution Reporting API does not support this method, as it does not allow the registration or broadcasting of triggers to Chrome instances using the same email.

To enable this functionality in the future, we must capture shopping behaviour within the browser and simultaneously track offline sales on the server-side.

To achieve Offline attribution, we propose to either :

• Implement a method to broadcast triggers to browsers
• Explore off-device attribution techniques, such as provided by IPA and other measurement proposals

While these alternatives would enhance Offline attribution, they would also facilitate Cross-device attribution. Do you anticipate the implementation of any of these options in ARA, or do you have any other suggestions for measuring offline to online attribution?