1. A method of graphically presenting the parameter sensitivity of a sub-circuit representation of a non-linear device, comprising: selecting a model of the sub-circuit dependent upon a plurality of model specific parameters; selecting from the model specific parameters a set of input variables to be presented; selecting a simulation target set to display, wherein the elements of the target set are derivable from the response characteristics of the sub-circuit as determined by the model; and dynamically providing a graphic representation of a simulation target set upon based the values of said input parameters chosen from said parameter range.