This consideration led us to propose a different approach to measure the bias of word occurrences in a discrete way: that is, we only take words whose occurrences are saliently biased in D(T) into account, and let the number of such words be the degree of bias of word occurrences in D(T).
sAL(D(T), s), the number of words in D(T) whose saliency is over a threshold value s, is expected to be free from the background noise and sensitive to number of major subtopics in D(T).