I ran some A-B testing for a customer this month, and Adsense revenue was up and down as we tested. Finally we thought we had the right answer and ran live tests on the customers high traffic adsense website. Some days adsense revenue was up, but overall adsense revenue was down. More on that in a minute.

The customer asked about Google Adsense publisher ID. Why does his login page say pub-1234567891 (just an example) as his Adsense publisher ID but the ads say CA-Pub-1234567891 as his Adsense publisher ID, and which on should you use for themes that ask for your adsense publisher ID?

So I googled Adsense publisher ID, and went to the Google website where I thought i would find the best true answer to which Adsense publisher ID he should type in on the admin page of his WordPress blog. I did not find an answer. Some guesses about Adsense publisher ID, CA-pub and Pub-, but no answers.

The right answer is to use the publisher ID that shows in the upper right hand corner of your adsense login page. Use pub-1234567891 (just an example), and it will work fine. Use it in the old ad format too. You can use a custom channel with the old Adsense ad format. Just make a Google Adsense custom channel and write down the number. Then put the custom channel number in the ad.

Back to live tests on the customers high traffic adsense website. I will say this one more time. The Google Adsense heatmap does not work for all websites. If I want an answer, like which Adsense publisher ID to use – ca-pub- or pub-, I find myself scrolling right past the ads so I can read the content. Top banners, 336 ads above the fold, but also above the content, are scrolled out of my way. I never read that stuff.

Secondly, if I land on a WordPress tag page or index page, pressing “read more” puts me below the ad in the actual article. In this case if it is your blog, use functions.php to stop that from happening.