Matteo DOT Redaelli AT gmail DOT com http://www.redaelli.org/matteo/ Code and suggestions from http://www.inside-r.org/howto/mining-twitter-airline-consumer-sentiment Hu and Liu’s “opinion lexicon” categorizes nearly 6,800 words as positive or negative and were downloaded from Bing Liu’s web site: http://www.cs.uic.edu/~liub/FBS/opinion-lexicon-English.rar