4. Mapping America’s emotional stateMovie Camera
Psychiatrists aren’t running machine learning on their patients’ Twitter profiles – yet. But large volumes of tweets can be used to make assertions about the happiness of large groups of people. A sentiment analysis run by Alan Mislove of Northeastern University in Boston measured every public tweet posted between September 2006 and August 2009, using a psychological word-rating system to identify happy or sad tweets. It turns out that the US west coast is happier than the east. Happiness peaks each Sunday morning, then dives to an all-week low on Thursday evenings.