It is common practice in the adtech industry to offer attribution and contribution reporting.

• Attribution typically refers to the Campaign that received the final touchpoint, or any other attribution model utilized by the adtech.
• Contributing campaigns are those campaigns with which the user engaged, but did not receive the attribution.

An attribution model like last touch tends to benefit Re-marketing and Search campaigns, while contribution emphasizes the positive influence of Awareness campaigns such as Video or Branding campaigns.

As outlined in this resource, it appears that the Attribution Reporting API (ARA) currently lacks the capability to provide contribution reporting. This limitation could significantly impact branding campaigns and potentially introduce a bias towards lower funnel campaigns.

Could you kindly confirm whether ARA supports Contribution reporting?

Additionally, could you provide guidance on potential workarounds for overcoming ARA limitations in scenarios like these? Shared Storage could be used for such use cases, but is highly impractical due to the budgeting drawbacks (such as shared budget for all sources & advertiser).