On Tue, 27 Mar 2012, clarodina clarodina wrote: This is a calculation that's probably easier to do using a spreadsheet, but you can do it in gretl: matrix A = {10,55,60,30,80,43,100}' matrix A39 = 39*ones(rows(A), cols(A)) matrix A61 = 61*ones(rows(A), cols(A)) matrix Atest = (A .> A39) .* (A .< A61) print Atest scalar n_40_60 = sumc(Atest) or, if you prefer matrix A = {10,55,60,30,80,43,100}' n_40_60 = 0 loop i=1..rows(A) --quiet n_40_60 += A[i] >= 40 && A[i] <= 60 endloop print n_40_60 -- Allin Cottrell Department of Economics Wake Forest University, NC