5.8 Prove that the Wilcoxon signed-rank statistic TT based on a set of nonzero observations X1,X2, .

5.8 Prove that the Wilcoxon signed-rank statistic TþT based on a set of nonzero observations X1,X2, . . . ,XN can be written in symbols as XX 1ijN sgn(Xi þ Xj)

where sgn(x) ¼

1 if x > 0

1 if x < 0