This is normally an internal function, but it can be overloaded to extend simr to other packages.
doFit(y, fit, subset, ...)new values for the response variable (vector or matrix depending on the model).
a previously fitted model object.
boolean vector specifying how much of the data to use. If missing, the model is fit to all
the data. This argument needs to be implemented for powerCurve to work.
additional options.
a fitted model object.