We choose a Chinese corpus as the primary document collection because Chinese text (as well as other Asian languages) has a very large term set and a satisfying subset is usually not smaller than 50000 (Li et al., 2006); on the contrary, a dimensionality lower than 10000 suffices a general English text categorization (Yang and Pedersen, 1997;Rogati and Yang, 2002).
relatively, probability ratio (Forman, 2003) is a more straight metric of discriminability.