Google's ad quality changes imminent

Google headquarters in Mountain View, Calif.

(Credit: Stephen Shankland/CNET News.com)

Attention advertisers: a promised change to Google's AdWords quality-judging method will take effect in coming days.

The change adjusts Google's calculation of advertiser's quality score--a key factor in determining how much the advertiser must bid to ensure ads are placed next to search results. With the new system, quality is calculated at the time a Google user performs a search, though historical data such as an advertiser's click-through rate still factor into the equation, Google's Trevor Claiborne said on its AdWords blog on Monday.

Given the size of the industry that's grown up around Google's search-ad system, any changes can cause indigestion in the search-engine marketing (SEM) business. Google tried to encourage people to look at the big picture, though: "These improvements are part of a continuing effort to deliver relevant ads to our users, and also to provide you with more control over your bidding and more insight into the quality of your ads and keywords," the company said.

Another change replaces the "minimum bid" price with an estimate for how much a particular advertiser would have to bid for ads to show on the first search page.

"Queries with a high level of advertiser competition may have significantly higher first page bid estimates, because you'll likely need to bid above the old minimum bid to rank higher than your competition and show on the first page," Google said. "Remember that you can bid less than your first page bid estimate and still show on subsequent pages--as long as your keyword is relevant to our users."