Pop-up/under ads pose a measurement puzzle

NYTimes discusses the recent statistics reported by Media Metrix indicating that x10.com is the fourth-most-visited site on the Internet. The reason so many people visit X10's Web site and the reason Nielsen/Net Ratings does not count much of the company's traffic is that X10 uses an advertising technology that opens an X10 Web page on a surfer's computer screen, whether the surfer wants it there or not. ... But several leading publishers support Nielsen/NetRatings in its contention that an advertisement is not in itself a Web site, even if it pops up in a separate window. ... "At the end of day, advertising is sold based on these sites," Ms. Young said. "It is intentionally misleading to include demographics based on advertising on a site like X10." Nielson/Net Ratings has created a series of filters so it will not count windows that contain only a single advertisement, although it concedes its approach is not foolproof.