Hello, Im am trying to fit a GAM (mgcv) using the family gamma and get the followinr error message: Error in gamma(link = "identity") : Non-numeric argument to mathematical function Does anyone know why do i get this? I tried to check in R-help already but I couldn't find anything alike. The code I used was: por <- gam(Bal ~ s(D)+s(S)+s(C)+s(H)+s(T), data=Balomit, family=gamma(link="identity")) Thx for your help, Marina [[alternative HTML version deleted]]