19. The method of claim 18 , further comprising acquiring a set of polar adjectival terms from a corpus of reviews, each of the reviews in the corpus including text and an associated rating provided by the author of the review and incorporating the polar adjectives into the polar vocabulary.
20. The method of claim 19 , wherein the acquiring of the set of polar adjectival terms comprises: extracting textual content from reviews in the corpus of reviews; identifying a set of frequent nouns from the textual content of the reviews, extracting adjectival terms from the textual content of the reviews, each adjectival term being associated in the textual content with one of the frequent nouns; and generating the set of polar adjectival terms including at least some of the extracted adjectival terms, a polarity measure being associated with each adjectival term in the set which is based on the ratings of the reviews from which the adjectival term was extracted.