The robust rank-order test tests the hypothesis that the medians of two distributions are the same without assuming that the underlying distributions themselves are the same. See S. Siegel and N. J. Castellan, Nonparametric Statistics, 2nd ed., 1988, pp. 206-215. The call is
CALL RROT(X,Y,M,N,U,IER)where X = a REAL*8 array of sample values, dimensioned X(M) (input)