From CNET News: The disappearing act came when Nielsen/NetRatings, a leading company in measuring Internet traffic, sharply cut its previously reported statistics for the financial Web site Entrepreneur.com to 2 million unique visitors in April, from 7.6 million.

Why the change? For millions of Web surfers, Entrepreneur.com visited them--and not the other way around, the measurement company said.

As computer users visited other sites, new browser windows popped up containing articles from Entrepreneur.com, according to Scott Ross, senior product manager for Nielsen/NetRatings.

Pop-up windows appear all over the Internet, including the Web site of The New York Times. But they are typically used as advertising to pitch a product or a service.

Entrepreneur.com's pop-ups were unusual because they contained news content, like articles on how to start a small business, making them hard to distinguish from an intentional visit to Entrepreneur.com's site. This hailstorm of pop-ups more than tripled Entrepreneur's reported traffic before it was detected and factored out a month later.

The technique of using pop-ups to gain readers underscores just how important sheer numbers have become in the online media business. Advertisers are shifting their marketing dollars to the Internet, but the rates they pay are low compared with traditional media.

View: Full article (CNET News)