[disgruntledphd2]

These studies exist, but tend not to be published. Essentially there's little to no commercial benefit from publishing, so people tend not to.

Like, I would argue that 80-90% of Goog/FB revenue is correlated with sales. This may be done badly (often), but it is done.

[buboard]

So how do advertisers find out who has the most effective ad system if they re not getting published? They choose in the dark?