It's not so hard to figure out if one particular person — or a small group of people — is happy or sad. Psychologists hand out questionnaires or conduct interviews. But when it comes to gauging the happiness of an entire society, things aren't so simple. Applied mathematicians Peter Dodds and Christopher Danforth of the University of Vermont in Burlington wondered if the Internet could help.

The duo focused on two popular outlets for personal expression: blog posts and song lyrics. Besides providing large slews of data, the researchers believed that people are more honest in personal writings than during formal psychological tests. The scientists analyzed sentences from 2.4 million blogs, which were collected by a Web site called www.wefeelfine.org. The site searches blogs across the world for versions of the phrase "I feel" and then records the entire sentence. For songs, Dodds and Danforth downloaded more than 230,000 lyrics from www.hotlyrics.net, a searchable online database of song lyrics submitted by volunteers.

Click here to read this article.