:
) ;
) (, , );
) ( , );
) ( ) ;
) ;
) .
. - , ; -1 +1. 0 , +1 .
:
- - () ;
- (Pearson product-moment correlation) - , ;
- (Spearmen's rank-order correlation) - , () ;
- - (point-biserial correlation) - , , , - ;
- j - , , .
- () (tetrachoric) - , , .
Xi Xj :
,
Xi Xj ; mXi mXj ; σX σX .
:
,
:
,
i =1, 2,..., n, j = 1, 2,..., m, u = 1, 2,..., N; N ( ); xi, xj ; SXi, SXj .
Xi Xj . [5].