I understand in most sites the 336 gives good CTR which means good earnings. However, my site isn't really designed to accommodate a 336 unit so I'd rather use a 468. However, with only ONE ad unit at a time on one of my sites, the 336 averages 260% more per click!! I don't know if Adsense allows me to post the actual average CPC for my site, so I used the percentage. This makes zero sense. In theory, the 468 should have higher CPC because there's only two ads showing on the page instead of four. I really don't want to use the 336, the CTR is awful because it just doesn't fit in my site. Bizarre. PS I don't think it's due to different image ads, I've never seen an image ad in either of my units ever.
well,what I understood is that you are comparing 2 different sites. Just dont forget the niche & content factor. Also you need to compare both clicks at the same time as the keywords bids keep goin up & down!