Critics of the mainstream media have long accused journalists of living in a "bubble" that doesn't reflect the rest of the country. A new study indicates that may be true, especially when it comes to Washington D.C.-based reporters.

The study's report, authored by University of Illinois journalism professors Nikki Usher and Yee Man Margaret Ng, suggests journalists "may be even more insular than previously thought," raising "additional concerns about vulnerability to groupthink and blind spots.”

"Most of the time, what happens on Twitter does not reflect the real world," Usher told the Illinois News Bureau. "But in the case of political journalism and political elites, generally speaking, what happens on Twitter is reality.”

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The study selected a sample of more than 2,000 D.C. journalists and observed more than 133,000 tweets between February 1 and March 31, 2018. Based on those interactions, the study found nine prominent community "clusters," classified by the following names: "elite/legacy," "congressional journalism," "CNN," "television (producers)," 'local political news," "regulatory journalism," "foreign affairs," "long-form/enterprise," and "social issues."

The "elite/legacy" community was the largest, making up 30 percent of the journalists examined. Those journalists worked for outlets including The New York Times, The Washington Post, NBC News, NPR, and Politico.

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"Congressional journalism" was the second-largest group, making up 20 percent of the sample. Outlets represented here included Politico, Bloomberg, The Associated Press, The Wall Street Journal, CQ/Roll Call, and C-SPAN.

The study found the "CNN" cluster was large enough to separate from the "television" cluster, which includes journalists from ABC News, CBS News, and Fox News. The study notes CNN anchor Jake Tapper was "the most influential journalist in our network as measured by weighted in-degree" with his 2.6 million Twitter followers.

However, Usher suggested that the massive CNN Twitter community is problematic.

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"CNN is telling a story about what is happening with CNN, and that is worrisome," she explained. "Maybe that’s an organizational branding strategy, but I think it potentially has deleterious effects for public discourse."

In summing up the study, Usher told the Illinois News Bureau, “Political journalists in D.C. are people who use Twitter all day. And so the question is what does that do to how they think about the world. And generally... it seems to me that it can make things worse.”