The problem with site analytics

If, like me, your blog uses eXTReMe Tracking, Site Meter, and Google Analytics, you already know what the problem with site analytics is; the three different services give you three different sets of numbers. Clearly site analytics is as much of an art as a science.

This was brought home to me as manager of Warren Mosler's US Senate campaign. My duties included analyzing our web site statistics to, in addition to other things, judge the effectiveness of our online advertising campaign. Where was our traffic coming from? Which advertisements sent us the readers with the highest level of engagement? And how to account for the discrepancy between the reports sent to us by our advertising venue, and our own site statistics?

We need more information by the providers of site statistics and analytics as to how they detect hits and referrals and measure engagement.