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"Great post Shad.  I agree, it's not always about CPA and it's not always about CTR when evaluating ad copy tests, which is often difficult to explain.\n\nNot to complicate things, but perhaps another factor here, as it is always, is quality score. If a better CTR, the keyword-ad variation pair should have a better quality score, and therefore a lower CPC  or higher position, which would affect CTR and CPA."^^<http://www.w3.org/2001/XMLSchema#string>
<https://www.pointit.com/blog/ad-copy-testing/>