Quality Score, AdWords Quirk In Delivery

We had a problem with our PPC campaign recently. Even though we had unoptimised the ad delivery we noticed one ad getting more traffic than the other. Now this did not seem like what should happen so we contacted Google thinking maybe we had found a bug in the delivery system.

In actuality we had found an impacting variable that is not generally known. Quality scoring impacts the delivery of your ads - one can get a better score and that will influence delivery even when asking for even flighting.

Obviously the QS impacts the real CTR - but behind the covers.

A rep at Google explained it this way:

Regarding the serving, this actually is a common question that we receive. The system tries to equally rotate ads but there are other factors that weigh into this rotation. In your case it does look fairly even for the most part, however the system may be looking at the one ad as one with a less quality score than the other, thus not serving it as often. Although you have it opted into rotate more evenly it isn't guaranteed that the system will functionally work to an exact science. I know this isn't the answer you were hoping for, but this is what we have been told by engineering!

Figured I would pass this along for comments. I have opened a forum thread here.

About the author

Frank Watson has been involved with the Web since it started. For the past five years, he headed SEM for FXCM -- at one time one of the top 25 spenders with AdWords. He has worked with most of the major analytics companies and pioneered the ability to tie online marketing with offline conversion.

He has now started his own marketing agency, Kangamurra Media. This new venture will keep him busy when he is not editing the Search Engine Watch forums, blogging at a number of authoritative sites, and developing some interesting online community sites.

He was one of the first 100 AdWords Professionals, a Yahoo and Overture Ambassador, and a member or mod of many of the industry forums. He is also on the Click Quality Council and has worked hard to diminish click fraud.