Let C(c, w) be the set of bigrams in the bigram lexicon that satisfy the condition of class c for word w, and let S(c) be the set of bigrams whose polarity is the one predicted by c. The precision of w with respect to c can be defined as: The above formula gives uniform weights for all the bigrams in C(c, w).
we found that it is beneficial to also take into account the uncertainty stemming from the automatic sentiment prediction of the unigrams and bigrams.