Optimized ads - Strange Results

Ads with lowest CTR have lowest CPC

[nyet]

We have been trying new ads for a month now. There are 3 in circulation. They each get about the same delivery (approx 30%)

Consistently the ones with the lower CTR also have a much lower CPC. (like 20% lower cost for .2% lower CTR)

The differential is large enough I am tempted to shut off the better performing ads to get better ROI.

What is wrong here? Shouldn't the higher CTR ads get *lower* CPC?

[mike_ppc]

Sounds strange indeed. Too bad you cannot see Avg.Pos for each ad. It would help a lot.
Still, the difference of .2% in CTR doesn't seem significant.
I'm just curious. What Avg Pos has the AdGroup?

[inasisi]

As much as I know, it is not the CTR for the Ad but the CTR for the Keyword that affects the CPC. So while calculating the Ad Rank for a particular keyword, the average CTR of all the ads for that keyword is used. (AWA or eWhisper might confirm)

But as per that logic, the CPCs of all the Ads must be the same and can't explain the difference that you're seeing unless the number of clicks is very low and a few high cost clicks might have skewed the numbers.

[nyet]

Thanks for the response. We get hundreds of clicks per day and as you suggest I initially chalked it up to the "noise" of one ad drawing more clicks on expensive words. But after a month and many thousands if clicks I would have expected it to settle out.

I guess I could try to correlate the ad text in question with the more expensive words and see if that is skewing things throughout. Perhaps it is a good thing?