Abstract
The research on similarity methodology of dynamic tracing disciplinary themes based on improved similarity algorithm is the improvement and perfection of current similarity methodology based on co-word analysis, and also is good supplement to the mapping method of dynamic tracing disciplinary themes based on co-word analysis. Statistical correlation coefficient is the key arithmetic when analyzing theme evolution. There are two kinds of methods used to compute the statistical correlation coefficient, and every method consists of some types of arithmetic again. This paper respectively had the comparative research on correlation coefficients belonging to corresponding large class and two large classes. Thus, we established the basis for the subsequent process in the analysis of theme evolution.