[chops]

This is definitely interesting. I know I'd be more inclined to click something that looks like that ridiculous paint drawing. But this bit bothered me:

Results? 0.049% CTR vs. 0.137 CTR

I hope I'm not the only one confused by this, but the lack of a percent symbol on the 0.137 means he went from 0.049% to 13%, an improvement of almost 300x.

Is this a typo? Did he mean to say he increased his CTR to 0.137% or did he actually increase his CTR by 300x?

Edit: Why is this being downvoted? It's a legitimate question.

[jdkramar]

This also bothered me. Just reading through his blog post makes it clear that proper English isn't very high on his list of priorities.

[benpof]

Whoops, my bad, it's been fixed with the % sign.

[tripzilch]

You might also want to consider using promille (per 1000) or something similar, when dealing with such tiny percentages. (I don't mean they're tiny for a CTR figure, just that small numbers like that are harder to get a gist of than "1.37 clicks for each 1000 views".