Rely on syntactic or co-occurrence patterns in large corpora. (Hazivassiloglou and McKeown, ACL-97; Turney, ACL-02; Yu and Hazivassiloglou, EMNLP-03; Kanayama and Nasukawa, EMNLP-06; Ding and Liu SIGIR-07)
Can find domain (not context!) dependent orientations (positive, negative, or neutral).
(Turney, ACL-02) and (Yu and Hazivassiloglou, EMNLP-03) are similar.
Assign opinion orientations (polarities) to words/phrases.
(Yu and Hazivassiloglou, EMNLP-03) is different from (Turney, ACL-02)
use more seed words (rather than two) and use log-likelihood ratio (rather than PMI).