Left, Steve Mack/Getty; Slaven Vlasic/Getty

Active users of Twitter are revealing their political leanings even if they are careful not to post about politics, a group of researchers at Duke University says.

Their research stems from an effort to rank 2010 primary candidates by political ideology. The researchers — David B. Sparks, Frank J. Orlando and Aaron S. King — analyzed whom politicians were following on Twitter, and who followed them. They then ranked the politicians on a political spectrum from the far left to the far right; the results dovetailed with ideological ranking systems based on the politicians’ voting records.

The idea that someone could divine the political ideology of someone who is using Twitter as a political tool is hardly a surprise. But Mr. Sparks said what was surprising about their study was that even public figures who are not openly political, and private citizens who use the site primarily as a social tool, reveal their political leanings through whom they choose to follow, and who follows them.

“If we included your Twitter account,” he told a reporter, “we could come up with a scaling for you.”

Much of the discussion about over-sharing on social networks has focused on users not being able to escape from something they have said online. But a person’s connections are also revealing, as this research found.

Other recent research shows that Twitter users congregate based on their mood. Of course, people have always gravitated toward the like-minded. Yet the idea that an instantaneous computer analysis could rank your relative conservatism or liberalism could be discomfiting for those who would like to remain out of the political debate, or who strive to remain politically neutral.

The Duke analysis started by comparing the networks of a large number of Twitter accounts. The accounts of those in the political center will have networks that look similar, while the more liberal accounts will have progressively less in common with the more conservative ones. The two accounts that have the least in common will be the most conservative and the most liberal. Among members of the House of Representatives those accounts belonged to Michelle Bachmann and John Conyers, respectively.

The research, which will be presented in April at the Midwest Political Science Association conference, also ranked public individuals and media organizations. Kelsey Grammer’s Twitter account, for instance, consist largely of reposted messages from people calling for a reunion of the television show “Frasier.” But the analysis still identified Mr. Grammer, who supported George W. Bush and has more recently thrown his energy into a conservative television network, as right of center. It plotted Katie Couric of CBS News as only slightly less liberal than the Daily Kos, a blog for Democratic political strategy. You can see the complete rankings of Congressional candidates, media figures and political organizations here.

This strategy did not prove useful when applied to corporations like Wal-Mart or Starbucks (or The New York Times) because their connections were too broad and not personal enough, Mr. Sparks said. But for individuals, he said, it can be quite telling.

“We don’t need to make any potentially arbitrary judgments about what constitutes left or right, and we don’t need to look at the words users are using, or anything like that,” he wrote in an e-mail. “The order just emerges from the patterns in followings.”