So in my earlier post about using php setcookie() for an adsense test. I set up a test to see whether traffic sent to my site from Google behaves different to traffic sent to my site from non Google domains. The results are out and confirm my thoughts that Google users are more likely to click on Google Ads.
The bars on the above graph show the impressions given to Google referred traffic and impressions to non-Google referred traffic (totals for both are >100k impressions and >1k clicks). The lines show the CPMs acheived by each type of traffic (the last point on the red line is skewed by a new test I just started). Quite clearly the RED line (google traffic CPM) is higher than the PURPLE line (non google traffic CPM) and so Google referred traffic eyeballs on Google AdSense are more valuable than non Google traffic (hardly the biggest shock in the world).
The data is a bit richer than this though when you dig just one level deeper and look at CTR% and CPC and what exactly is driving the higher CPM from Google.
The above graph shows CTR% for Google and non Google referrers. The Google user's CTR is significantly higher than non Google users.
This graph however shows the CPC for Google and non Google traffic to my site and the non Google traffic tends to win out (have a higher CPC) or be the same. So essentially clicks from traffic sent to my site by other search engines than Google, direct visits or links on other sites are equally or more valuable than those from Traffic sent to my site by Google however traffic sent to my site from Google is far more likely to click on Google ad's than other traffic. It would be nice to test this with YPN! but they keep turning me down for membership. So for now I may rotate in Valueclick banners rather than adsense ads in some places for non Google traffic.
There are more tests to come and I am getting quite excited about them since the latest test I am running on ad positioning seems to have shown me how to triple my Google AdSense earnings (thanks Keith).
Above all this test has taught me one thing. I am massively frustrated with only 200 channels in Google Adsense for Content. This is far too low to do the testing I want to do real time, all the time, I can only run 7 AB tests on different variables at the same time and only 3 tests with 4 variables or two tests with 6 variables. What about Geography, hour of day, colour, shape, size... I want to run complex tests and really understand the interplay of variables and if I was say New York Times I would want to do that even more.
I am exploring AdLogger as a solution and similar tools but come on Google, you guys know data, you guys are excited by the interplay of variables, why not let me get access to that data and really play with it?