By counting and reporting only those ads that load in the browser, the technique is more accurate, proponents say.
The system will count and report ad impressions only after the ad's graphic loads in the viewer's browser. Ads within blocked pop-ups, for instance, would not receive credit. Most Internet publishers currently measure their ad impressions at the other end--when they leave the server.
The new process will "measure even more accurately if an advertisement has been viewed by a consumer," Todd Teresi, Yahoo's vice president of operations, said in a press release.
The system hinges on new standards for tracking ad impressions, released last November by an Interactive Advertising Bureau task force, which Yahoo chaired.
The guidelines marked the first time any advertising medium had developed a standard tied to the point at which the ad reaches the consumer. Other mediums, such as magazines and television, measure ad impressions through the content or programming that houses the embedded ad.
According to a company press release, Yahoo is one of the first organizations to put the standards into practice. Now available in the United States, Yahoo's measurement system will make its way across its global network by early next year.
Separately on Monday, Yahoo Search Marketing announced a partnership with Web analytics providers Coremetrics, Omniture, WebTrends and WebSideStory.
The agreements will allow the analysts to access marketing-campaign reports through application program interfaces that were developed by Yahoo and interact directly with Yahoo systems. The analysis companies in turn will make a greater amount of their click-activity information available to Yahoo.
Yahoo said in a press release that it plans to make this option available to other Web analysts in the future.