A business use-case, and outline of a proposal

Hello everyone,

We've just published a new explainer to the github repo: https://github.com/w3c/web-advertising/blob/master/privacy_preserving_multi_touch_attribution_and_cross_publisher_lift_measurement.md

We attempted to follow the group's recommendation to:

  1.  Explain a current business need
  2.  Explain why it is important
  3.  Explain how it is done today
  4.  Outline at a high level how this might be achieved in a privacy-preserving manner

We cover two tightly linked business needs:

  1.  Multi-touch-attribution across publishers
  2.  Cross-publisher-lift measurement

We present these together, because the latter is used to calibrate the former.

While we have suggested a mechanism for implementing the latter (it only requires a minor modification to our previous lift measurement proposal), we have not provided any suggestions on implementation details for the former. We are hopeful that the platform providers will help us find solutions!

That said, we are fairly confident that a privacy-preserving approach ought to exist.

We are looking forward to discussing this on Thursday, and working with the group to develop new APIs that serve advertiser business needs in privacy-preserving ways!

--Ben