Is Twitter a valid tool for measuring happiness?

By Deborah Kotz, Globe Staff

With nearly 200 million Twitter users who send 65 million tweets each day, it was almost a given that scientists would start analyzing tweets to measure our happiness level and how it’s trending over time. In a depressing bit of news, University of Vermont researchers found that we’re trending downward in our mood -- or at least in the positive language we use to express ourselves in tweets. I’m just wondering if the findings are valid.

In the study published in the December issue of the online journal PLoS One, the researchers developed a software tool to assign happiness scores to 4.6 billion tweets over a nearly three-year span -- based on measuring the frequency of more than 10,000 words used to signify emotion or a positive or negative experience.

What they found is a gradual upward trend in happiness from January to April 2009 followed by a slow gradual downward trend that accelerated a bit during the first half of this year. Happier tweets increased toward the end of the year around the holidays and dropped back down in January.

We also tend to be happier on the weekends, in terms of our peppy tweets, and turn to negative spin on Mondays -- no surprise there for those dreading a long work week.

Certain occasions caused spikes in happiness tweets, including Christmas, New Year’s, and Valentine’s Day. “The only singular, non-annual event to stand out as a positive day was that of the Royal Wedding of Prince William and Catherine Middleton, April 29, 2011,” the researchers wrote.

Tweets expressing sadness surged after news about Michael Jackson’s death, the devastating March earthquake in Japan, and the 4-to-1 victory of Germany over England in the 2010 soccer World Cup. (The researchers analyzed tweets only in English; no doubt, the German tweets trended toward the joyful.)

Interestingly, “reports of the killing of Osama Bin Laden on May 2, 2011, resulted in the day of the lowest happiness across the entire time frame,” reported the researchers. They didn’t provide an explanation as to why, but I’m guessing that tweets were more wistful reflecting on the 9-11 tragedy that he caused.

About an hour after hearing the news, my cousin posted a message on a social media site that said when her kids woke up she’d have to tell them that the man who killed their daddy was dead. (Not much happiness there.)

While this study is certainly food for thought, I’m not certain how much stock I’d put in it for measuring our overall life satisfaction, as opposed to just our reaction to the news of the day. What do you think. Should researchers use Twitter to get a better look at the national psyche? Is it a valid tool?

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.