The review was conducted by the Project for Excellence in Journalism, an institute affiliated with the Columbia University Graduate School of Journalism and financed by the Pew Charitable Trusts.

As part of the review, a special study looked at how a variety of outlets, including newspapers, television, radio and the Internet, covered a single day's worth of news and concluded that there was enormous repetition and amplification of just two dozen stories. Moreover, it said, "the incremental and even ephemeral nature of what the media define as news is striking."

On May 11, 2005, a date that was chosen randomly, Congress was debating the appointment of John Bolton as ambassador to the United Nations, the actor Macaulay Culkin was testifying in Michael Jackson's molestation trial and car bombs in Iraq killed 79 people.

On that day, the study said, " Google News offers access within two clicks to 14,000 stories, but really they are accounts of just 24 news events."

The coverage offered by 57 media outlets was examined in depth in three cities (Houston, Milwaukee and Bend, Ore., which were randomly chosen from lists of cities of different size and geographical location) and showed certain shared characteristics depending on the medium.

Print and the evening network news, for example, focused on the violence in Iraq, a false alarm in Washington involving a small plane that violated restricted air space, and protests in Afghanistan.

Cable television and the morning news programs highlighted Mr. Jackson's trial and a murder in Illinois; local television and radio produced a steady diet of weather, traffic and local crime.

The blogosphere, meanwhile, shrugged off most of the breaking news, focusing largely on broader, longer-term issues.

"Contrary to the charge that the blogosphere is purely parasitic," the study said, bloggers raised new issues. But they did almost no original reporting: only 1 percent of the posts that day involved a blogger interviewing someone else and only 5 percent involved some other original work, such as examining documents.

Cable news was the "shallowest" and most "ephemeral" of the media, the study said. Newspapers, which are the biggest news-gathering organizations, covered the most topics, provided the most extensive sourcing and provided the most angles on particular events, it said, "though perhaps in language and sourcing tilted toward elites."

Many of the national broadcast reports quoted the same few people.

"More coverage, in other words, does not always mean greater diversity of voices," the study said. "Consuming the news continuously does not mean being better informed."

Tom Rosenstiel, director of the project, said that reporters seemed to be increasingly shunted off to an isolated area while covering events, as they were during the recent mining disaster in West Virginia, giving them little first-hand access.

"The irony is that having more reporters doesn't mean more coverage," he said. "It means more reporters crowded into one corner of the scene."