Emotional words contained in 300 million tweets suggest that the West Coast is happier than the East Coast, and across the country happiness peaks each Sunday morning, with a trough on Thursday evenings, computer scientists at Northeastern University have found, describing the technique as “the pulse of the nation.” 

To glean mood from the 140-character-long messages, they filtered the tweets to find ones that contained words included in a psychological word-rating system called Affective Norms for English Words – a low-scoring word on ANEW is considered negative, a high-scoring one positive.