A Measure of Term Representativeness Based on the Number of Co-occurring Salient Words

We propose a novel measure of the representativeness (i.e., indicativeness or topic specificity) of a term in a given corpus. The measure embodies the idea that the distribution of words co-occurring with a representative term should be biased according to the word distribution in the whole corpus. The bias of the word distribution in the co-occurring words is defined as the number of distinct words whose occurrences are saliently biased in the co-occurring words. The saliency of a word is defined by a threshold probability that can be automatically defined using the whole corpus. Comparative evaluation clarified that the measure is clearly superior to conventional measures in finding topic-specific words in the newspaper archives of different sizes.