Adjectives as indicators of subjectivity in documents

The goal of this research is to automatically predict human judgments of document qualities such as subjectivity, verbosity and depth. In this paper, we explore the behavior of adjectives as indicators of subjectivity in documents. Specifically, we test whether a subset of automatically derived subjective adjectives (Wiebe, 2000b), selected a priori, behaves differently than other adjectives. 3,200 documents were ranked by 100 subjects as being high or low in nine document qualities (Tang, Ng, Strzalkowski, & Kantor, 2003). We report a statistically significant correlation between the occurrence of adjectives in documents and human judgments of subjectivity. More importantly, we find that the subset of subjective adjectives is more strongly correlated with subjectivity than adjectives in general. These results can be used to identify document qualities for use in information retrieval and question-answering systems.