Hello, In comparing the following scripts, the matrix operations are much more time-consuming tasks. Is such a behaviour normal ? I was under the understanding that handling matrices is quicker than operations on series. :-[ cheers, artur nulldata 10000 series x = normal() series example = 0 loop for i = 1..$nobs --quiet example[i] = x[i] endloop matrix example2 = zeros($nobs,1) loop for i = 1..$nobs --quiet example2[i,1] = x[i] endloop -- Artur BALA development economist, consultant phone: +216 22 99 73 44 skype: artur.bala.tn email: artur.bala.tn(a)gmail.com *********************************