Scientists now using Twitter to measure happiness. What could go wrong?

The consistently happiest days are, not surprisingly, vacation days and holidays. The overall happiest days of the last few years were election day (Nov. 4) and President Obama’s inauguration (Jan. 20). On these days, people typically typed sentences with words like “pride” and “proud.”

Some of the saddest days over the last few years have been the anniversaries of 9-11 and even the day before that solemn anniversary, Sept. 10. Michael Jackson’s recent death also caused a drop in the average national happiness.