The magazine categories identified here were devised by the Project using Mediamark categories as a starting point. Mediamark, a company that studies magazine audiences, places every magazine it studies into a category. Some magazines occupy several categories at once. Newsweek, for instance, is classified as a "news publication" but also under "general interest." In cases like this PEJ picked the most appropriate category.

In some cases, such as The Economist, which Mediamark classified as a "business & finance" publication, PEJ disagreed. We classified The Economist, which calls itself "a weekly news and business publication," as a news magazine.

In all we created three categories based largely on Mediamark groupings. One was news magazines, which includes Time, Newsweek and U.S. News and World Report, as well as The Economist, The Atlantic, The New Yorker, National Journal and Jet.

Another was business, which includes Forbes, Fortune and Money, as well as a selection of other business magazines. The third was pop culture/entertainment/lifestyle, which includes People, Entertainment Weekly and Rolling Stone and a large selection of other books.

The categories we have created here are broad, with the news category in some ways being the broadest. We understand that news contains some publications not normally considered news magazines - such as The New Yorker and The Atlantic. There are two primary reasons for this broader news definition.

First, the news environment has changed and grown in recent decades (the arrival of the three 24-hour cable television networks and the Internet, just to name two changes). As a result we believe readers have reached beyond the traditional magazines for news. Broadening this category lets us consider that phenomenon.

Second, our source of data for ad pages and revenues, the Publishers Information Bureau, has a limited number of traditional "news" magazines on which it collects data. The major news/opinion journals, such as The New Republic and National Review, do not list with the Publishers Information Bureau. The other two categories, business and pop culture/entertainment /lifestyle, were fairly broad and we thought it was only right to make news a bit more comprehensive. Without broadening the "news" category the number of magazines in the group would have been extremely small and narrowly focused.