Advertising dollars are not the only part of the industry moving to the web—a venerable advertising trade magazine is starting to shift there, too.

Starting next year, Nielsen said it would decrease the frequency of Adweek from 49 to 36 issues per year. Meanwhile, the company plans to expand its Adweek.com website.

"We've seen our audience move online in terms of where they get their information," says Sabrina Crow, a senior vice president for the media and marketing group at Nielsen Business Media. This move is really an expansion to Adweek's content offerings, she says. One new element to the website will be exclusive Nielsen data.

This trend is echoed in the numbers. In 2006, Adweek had an average of 15 advertising pages per standalone issue, according to the company. In 2007, the average number of ad pages has dropped to 13, a decline of about 13 percent.

Circulation has also slipped. In 2005, its average circulation was 24,067 and was down to 21,271 for the six months ending in June 2007, a 12 percent decrease, according to BPA Worldwide, its circulation auditor.

Meanwhile, its website has nearly 5 times as many unique visitors as the magazine has subscribers. Adweek.com has seen an average of 103,500 unique visitors per month since January 2007, according to comScore Media Metrix. Before January, comScore didn't track its traffic. ComScore only starts counting a website's visitors once the site gets between 50,000 and 100,000 visits per month.

Adweek's sister publications Mediaweek and Brandweek also target the ad industry, but reach out to their specific niches in addition to Adweek's target audience of advertising executives. Neither has been steadily decreasing in circulation like Adweek. Neither is the subject of plans to decrease frequency.

Advertising Age, which is owned by Crain Communications, is Adweek's primary competition outside of The Nielsen Company. (Full disclosure: This reporter formerly worked for Ad Age.) Unlike Adweek, Advertising Age's average ad pages per issue and circulation have increased.

In 2006, each of Ad Age's 51 issues had an average of 20.7 ad pages, according to the company. In 2007, this number was up 16 percent to 24.1 ad pages.

At the same time, the magazine's circulation has increased from an average of 56,648 a week in all of 2005 to 58,893 for the six months ending in June 2007, according to the Audit Bureau of Circulations. Advertising Age said it has no plan to decrease its number of issues in 2008.

Meanwhile, its website Adage.com has gotten an average of 117,700 unique visitors per month since January 2007, according to comScore Media Metrix. But that's just about twice its current weekly circulation.

by Willow Duttge