Condé Nast's current campaign
talks up its chic readership

How many people visit a given site?

Answers may vary, depending on whether the site itself is providing the numbers, or third-party companies, like Nielsen//Netratings and comScore, are.

Since tracking companies omit certain results — like visitors behind office firewalls — their numbers are much lower the figures of media companies.

Condé Nast's internal count for Style.com was 1.8 million visits per month, while comScore quoted 421,000 and Nielsen reported 497,000, according to the New York Times.

Armed with raw data, web publishers accuse tracking companies of using small samples and not including enough of their core readers - like the fashion-forward and financially comfortable visitors that frequent Condé Nast sites.

Meanwhile, tracking companies blame online media for double-counting people who visit the site from the home and office, and mixing up international and domestic traffic.

Yet although web publishers say discrepancies stunt growth, the online ad market is expected to balloon to $20 billion, up from $9.6 million in 2004.

But while it's wise to remember that numbers vary depending on the source, disagreeing with the tracking company is an age-old battle going back to the days of TV, radio, and print.

Just ask Linden Lab, which hotly contested the numbers reported by Yankee Group, regarding Second Life, just recently.