Thanks a lot Bob for your clear explanation.
I am currently applying fixed-shape regression to my data. If I use the option -iresp, an error message appears saying: "only 1 time point for iprefix". I suppose that the -iresp option has to be used when running a variable-shape regression, while the -fitts option has to be used when running a fixed-shape regression. Am I right? Should I use the -fitts option to check how the fitted model looks against the real data?
Thanks again.
Bye
Silvia