Methods for Creating Semantic Orientation Dictionaries

We describe and compare different methods for creating a dictionary of words with their corresponding semantic orientation (SO). We tested how well different dictionaries helped determine the SO of entire texts. To extract SO for each individual word, we used a common method based on pointwise mutual information. Mutual information between a set of seed words and the target words was calculated using two different methods: a NEAR search on the search engine Altavista (since discontinued); an AND search on Google. These two dictionaries were tested against a manually annotated dictionary of positive and negative words. The results show that all three methods are quite close, and none of them performs particularly well. We discuss possible further avenues for research, an d also point out some potential problems in calculating pointwise mutual information using Google. 1.