Hi, I'm new to both MASON and Java programming so apologies if this is a bit simple. I have a simulation which runs nicely via the GUIState for single runs. In order to generate some data for stats analysis I'd like to get it to run the simulation multiple times without the GUI, and also pass in an automatically numbered filename to take output and a varying parameter value. From what I can see, the doLoop method is what I need but I can't seem to get my head round the syntax. Should I be writing the code within my Engine (extension of SimState) class or a wrapper class which calls Engine? Any help much appreciated! Ed Long