Hi, I know that the following question is a basic one,sorry in advance. My problem is that I have a data sheet with 80 variables which are unemployment rates of 80 countries. I call it as u1 to u80. Besides I have for the same countries their productivity rates. I want to do a kind of loop to select the time series of unemployment and productivity rates of country one,ie u1 p1 and apply a fuction to all of the paorwise variables, who can I do that in a efficient way? Thanks