I now agree with most of what you say - as you point out we were just looking at different parts of the same thing. Your aside comment is really interesting. I

I now agree with most of what you say - as you point out we were just looking at different parts of the same thing. Your aside comment is really interesting. I'm not sure what the solution here is - more accurate systems of measurement lose the tight feedback loop that make online ads so successful, but simpler measurement is wrong. Some sort of combination of the two is the answer, but how that exactly works in practice I have no idea!