Google is to limit the number of affiliate ads that show up in search results, as has been rumored over the past few weeks. Advertisers are now being notified of the change, and it will go into effect over the coming weeks, Google says.
With the change, Google will allow only one ad to lead to a particular web page per query, whether that ad be from an affiliate of the web site or the web site owner.
"We've seen and heard from users that there are many cases where we are showing the same creative with the same visible URL linking to the same page, said Salar Kamangar, director of product management at Google, explaining users don't like this. "Just like with search where we have duplicate removal, we want to make sure we aren't showing duplicated ads."
Which exact ad gets selected depends on which ad has the highest "Ad Rank" within Google's AdWords system. That is, the cost per click they are willing to pay multiplied by the clickthrough rate. If an official site has a higher Ad Rank than affiliates, then that will be the ad selected. If it is an affiliate with a higher Ad Rank, the affiliate ad will be shown.
The program will not prevent multiple affiliates for the same company from bidding on a term, as long as they want to drive traffic to their own sites. However, the affiliates will have to drive people to original content. Just linking to a page that has little content other than a link outbound to Amazon -- that isn't allowed.
The Up Close On Google Affiliate Ad Changes article for Search Engine Watch members provides additional details on the changes, along with some illustrations and examples of how things work now and what will be allowed after the change. If you're a member, be sure to check it out.
Want to discuss the changes or learn more from what others are discussing? Visit our forum thread: AdWords Restriction Of 1 Affiliate Per Merchant Announced. A copy of the letter Google sent out to advertisers is also posted in that thread.