A few hours later, competitor Media Metrix sent out a media advisory with the subject line "The REAL Top 25 Web sites," announcing that its top list of sites is due out this week.
As the stakes get higher in the Web measurement field, the claims do, too. So how are the measurement companies measuring up?
RelevantKnowledge, as well as new research company @plan, has brought competition to the important business of measuring traffic on Web sites, a field that until last summer was dominated by Media Metrix, formerly PC Meter.
And the competition will heat up even more in May or June, when Nielsen Media Research will launch a new Web measurement service now being tested with approximately 3,000 panel members.
Nielsen's service will be called NielsenNet or NielsenWeb, according to Manish Bhatia, director of interactive services for Nielsen Media Research.
As Web media buyers and sellers will attest, measurement is a critical factor for driving the business forward, and there's much scrutiny placed on the numbers.
"A lot of sites take these numbers to the bank," said Rich LeFurgy, chairman of the Internet Advertising Bureau and senior VP-advertising, for ESPN Internet Ventures.
So when ESPN's SportsZone site doesn't show up on the Top 25 list of either Media Metrix or RelevantKnowledge, it hurts.
Mr. LeFurgy says Media Metrix and RelevantKnowledge undercount SportsZone's numbers. Citing SportsZone's own log files for November, Mr. LeFurgy said the site served 168 million pages, while Media Metrix reported 41 million and RelevantKnowledge reported 94 million.
Mr. LeFurgy argues that neither panel has solid enough representation of work or education users, although the measurement companies say the discrepancy is a reflection of different ways of counting users, such as those who access the Web from both home and work.
Media Metrix has a panel of 30,000 home PC users who participate in monthly reporting (out of 45,000 total members), compared with RelevantKnowledge's most recent reporting panel of 3,000 users (out of 11,000 total).
NIELSEN WILL TRACK WEBTV
RelevantKnowledge uses random digit-dialing phone surveys to select its panel, while Media Metrix recruits its panel members via direct mail. Both say their panels are representative and projectable to the entire Web universe.
Media Metrix tracks not just Web site activity, but all online activity including America Online and other services, through software loaded on users' PCs. It requires users to send back their diskettes in the mail, while RelevantKnowledge tracks Web activity online. Media Metrix has 125 paying clients, while RelevantKnowledge has 25.
Nielsen's service will track Web activity across multiple platforms, including television, as demonstrated by its recent agreement with Microsoft to track activity on WebTV.
MORE THAN JUST A NUMBERS GAME
But are these services delivering what media buyers want?
John Nardone, director of media and research at interactive agency Modem Media, said he'd like to see more reporting on audience composition based on subsections of a site. Both Media Metrix and RelevantKnowledge say they can do this now, although RelevantKnowledge will need to boost its panel size so it can have a representative sample for these "basket" areas on sites. RelevantKnowledge plans to introduce a separate, larger panel this year, and it's now setting up panels in Germany, Norway and Sweden.
Media Metrix has several new ventures, including a reach and frequency model for new media; integrating its data with data processing system Telmar, metering a sample of technology users through a deal with Intelliquest; reporting on specific areas of sites; and providing local market data.
But even with these new services, the ultimate measure of a successful online campaign is hitting the right audience with the right message, and convincing them to respond. And that's more than just a numbers game.