Re: [private-measurement] Interoperable Private Attribution (IPA) (#9)

> One more question about IPA behavior. I want to confirm that attribution across multiple queries works correctly. Here's an example: imagine there's a single advertiser selling a single product, and is running 3 different campaigns for it. They want to use IPA to measure the relative performance of their 3 campaigns. This is my understanding of how this would work in IPA.
> 
> The advertiser will send 3 queries to the system:
> 
> {Campaign1's source events, all trigger events}
> {Campaign2's source events, all trigger events}
> {Campaign3's source events, all trigger events}
> If IPA treats these queries completely independently, then attribution does not take into account source events from separate queries. That is, a hypothetical user journey like {Campaign1 source event, Campaign2 source event, Campaign 3 source event, trigger} will end up contributing a count to each of the three queries above, causing double counting.
> 
> One way to make this work would be to first run "global attribution" with the union of the events in all the queries, and then separately evaluate each query separately from the pool of globally attributed sources/triggers. I couldn't tell if this was how the protocol was intended to work though.

In the event an advertiser wants to evaluate the relative performance of 3 campaigns (which they might have purchased from different ad-sellers) I assume that they would NOT issue three separate queries as you’ve shown. This would wind up hitting their differential privacy budget three times for the same set of trigger events. They’d be far better off running a single query with all of the source events from all three campaigns, and all of the trigger events. This would make much better use of their budget, as well as enable “global attribution”, where we can avoid double counting.

To be clear, I understand this is a significant departure from how things work today. Today Facebook ads manager shows just an FB view of things. In an IPA world, it would not be possible to show them this. It wouldn’t be an efficient use of their privacy budget. It would be much more similar to the mobile app ecosystem where advertisers utilize 3rd party “mobile measurement partners” that give them a unified view across all their ad buying channels, preferring to view reporting there and eschewing platform-specific reporting channels.

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Received on Monday, 9 May 2022 05:58:52 UTC