"For my 2� worth of opinion, I'd add that the difference is often how tightly focused each page you put up is. Look, your goal - beyond getting lots of traffic - is to have ads shown on your pages that are truly targeted to your topic on each individual page. Looking around the web, I see lots of pages with very generic AS ads showing. I'd bet a lot that they're the ones getting 1% or less CTR. If someone got to your site from a search engine where they searched for 'red plastic widgets' and your page is about all kinds of widgets, sure, a few will probably click your AS ads. But imagine how many more would click them if your page was all about red plastic widgets (and nothing else). They'll either buy from you, hit the back button, or click one of your highly targeted AS ads that should also be about that type of widget.
So my advice (as someone who averages well over 25% CTR on 11 sites) is to post pages that are extremely focused on one product, idea, or service. Don't stray. If you're tempted to transition into a related topic, put up another page about it! I'll bet your CTR shoots way up if you're stuck in the 1%-3% range right now." Swebbie
