Twitter Global Mood Ring Reveals Saddest Day on Record: Boston Marathon Bombings

It turns out that there's a global mood ring that measures the world's happiness and sadness. It doesn't use colors, though; instead, it uses Twitter. And what did it find? April 15, 2013, the date of the Boston Marathon bombings, was the saddest day on record in five years.

So how does it work? The financial-style "happiness" index categorizes words that are used in tweets in order to assess the mood of the population. It places negative words such as "sad," "victims" and "tragedy" firmly under the "sad" category. Positive phrases, such as "hahaha," are placed in the "happy" category. In this way, the researchers can actually measure daily global mood swings that are expressed via Twitter.

In fact, you can see how the world is feeling for yourself on the new public website, hedonometer.org. There, researchers publish the data that reveals exactly how the general population is feeling at any given moment. The site gathers about 50 million tweets from around the world each day. The words are then assigned scores from one to nine, nine being the happiest and most positive.

"We're trying to develop a complementary measure of well-being for society," said Chris Danforth, a mathematician at the University of Vermont who's helping to develop the site, in an interview with Discovery News. "We're trying to take advantage of people's expressions online and measure something that is really important."

It seems like the "hedonometer" actually works relatively well. While the saddest recorded day was April 15, the happiest day was Christmas in 2008. In fact, every Christmas seems to spike for positive terms on Twitter. The data also shows that people tend to be sadder on Mondays, but happier on weekends.

Yet the research doesn't only target overall happiness and sadness, it also reveals area-specific moods. The scientists were actually able to find that the happiest city in the U.S. was Napa, California, while the saddest happened to be Beaumont, Texas.

"Our instrument reflects a kind of quantitative macro-story, one that journalists can use to bring big data into an article attempting to characterize the public response to the incident," said Danforth in an interview with The Daily Mail.

Want to check out the hedonometer for yourself? You can see it here.