19. The text mining method of claim 6 , further comprising: (c) extracting the inherent portions based on the calculated degrees.
6. A text mining method for performing text mining on a first text data and a second text data, wherein each word of the first and second text data has a confidence, comprising (a) calculating a mutual information amount I(w i , w j ) at least based on a frequency of appearance of word w i in the first text data N 1st (w i ), a frequency of appearance of word w j in the second text data N 2nd (w j ), and a frequency of co-appearance of w i and w j in both text data N 1st,2nd (w i , w j ) using the confidence of w i and the confidence of w j ; and (b) using the mutual information amount I(w i , w j ) to calculate degrees to which w i and w j correspond to inherent portions of the first and second text data, wherein N 1 ⁢ st ⁡ ( w i ) = ∑ l ⁢ R 1 ⁢ st ⁡ ( w i , l ) , [ Equation ⁢ ⁢ A ] N 2 ⁢ nd ⁡ ( w j ) = ∑ l ⁢ R 2 ⁢ nd ⁢ ( w j , l ) , [ Equation ⁢ ⁢ B ] N 1 ⁢ st , 2 ⁢ nd ⁡ ( w i , w j ) = ∑ l ⁢ R 1 ⁢ st ⁡ ( w i , l ) ⁢ R 2 ⁢ nd ⁡ ( w j , l ) , [ Equation ⁢ ⁢ C ] R 1st (w i ,l indicates a confidence of w i for record l, R 2nd (w j ,l) indicates a confidence of w j for record l.