1) I'm suprised that this kind of work is going on at Microsoft, Google, Yahoo, etc. Maybe I'm just unaware, but I thought that was interesting. 2) The conclus

1) I'm suprised that this kind of work is going on at Microsoft, Google, Yahoo, etc. Maybe I'm just unaware, but I thought that was interesting. 2) The conclusion of this paper is daunting. It sounds like it's impossible to reliably know if a campaign was -10/+10% ROI. Only if the campaign was =50% was it then just 'difficult' and not impossible. Very cool stuff Randall and Justin.