Hi all, In process of learning the gretl programming interface I'm trying to write a stepwise regression procedure (btw, does this exist already?), and encounter strange results when I apply the -= operation to a list within a loop. So outside of a loop when I execute: xlist -= Z2 the Z2 variable is removed from the list xlist. Inside a loop, however, xlist only contains Z2 and not the other variables. I'm sorry if this has been posed before -- I just joined the group -- but what is the correct way to remove a variable from a list inside a loop? (That attached code demonstrates the point) Thanks! Itai.