URL channels. There are a lot of ways you can organize your AdSense campaign into channels. The simplest is by using URL channels, meaning each site you run has its own generic channel. Tracking is usually automatic–you don’t have to add anything to your AdSense code since Google will already attribute the ads to the URL of the site on which they were displayed.
You can use URL channel tracking to organize by subdomain or subdirectory, too. So if the your site is organized by URL structure, then this is a simple way to do it.
One problem with using URL channels to track performance is that the generic URL channel (such as the one for the domain) will also include earnings from the lower-level channels (such as subdomains or subfolders). You could since some of the earnings from subdomains or subfolders might get double-counted.
Using custom channels. Custom channels are better at tracking performance because you can specify a channel for almost anything you put your AdSense ads on.
Peresonally, I would do it this way: I’ll use channels for each of the areas I use AdSense on, such as my main/homepage, archives page, side bar, and single page content (particularly useful if you are using excerpts on your blog homepage).
This way, I can track which ads are better performing and which areas are better off without ads.
What’s even better is that you can now combine custom channels in one AdSense ad, so you can track performance using several groups.
For instance, on my blog homepage, I can have the “header,” “sidebar,” and “content” ads. I can set up a channel named “my blog homepage” to track the performance of these three ads in aggregate. Then I can also have each one with its own channel so I can track individually.
You can then play around with the positioning and placement of your ads, to see which works best revenue-wise.
