> To let those advertisers do the experiments themselves, and to relate the campaign to in store sales, would require Facebook and google to share a ton lot of

> To let those advertisers do the experiments themselves, and to relate the campaign to in store sales, would require Facebook and google to share a ton lot of internet-user tracking data I think you are misinterpreting what "do the experiments themselves" implies. Certainly there is a JOIN with Google's or FB's data, but it can still happen entirely in a hosted sandbox with no data sharing necessary.