what is the easiest way to get from > x x1 x2 [1,] 2 3 [2,] 3 2 [3,] 1 3 [4,] 1 4 the matrix xbar > xbar1 x1 x2 [1,] 1.75 3 [2,] 1.75 3 [3,] 1.75 3 [4,] 1.75 3 with the mean of the columns of x as values? thanks christoph -- Christoph Lehmann <lehmann at puk.unibe.ch> University Hospital of Clinical Psychiatry