[michaelochurch]

I'm not that surprised by the low score of 5/2/11, because double negatives are hard. It's actually hard to separate sentiment when interactions (such as double negatives) come up:

"A bomb killed a terrorist." Good news. Three negative words.

Many psychologists believe that the quickest parts of the human brain don't process double negatives at all-- that's why thinking "this is not going to kill me" doesn't help during a panic attack, but "this will end" does-- which is probably a small part of why news-watching (even positive news like Osama's death) makes people unhappy.

"My best friend has been killed by a heart attack." Three positive words. One negative. One (attack) that is slightly-negative but has energetic/positive connotations.

"My best friend defeated cancer" vs. "Cancer defeated my best friend." Similar tokens; opposite meanings.

What really surprises me is that it seems contrary to economic trends: in late 2008, when the economy was going to hell, the sentiment average goes up in a major way. Across 2009-13, while the economy slowly recovers, the sentiment level declines. Day-of-week average differences are very slight, but the more people are working, the more unhappy they are. This could mean that structurally unemployed people are self-deceptive, or tweet happier things because they have more time per tweet, or it could genuinely mean something.

[daned]

His research specifically mentions the classification of n-grams as a future area of work. (I have been working on implementing his work in python, so I have been diving into this over the past few weeks.)