Concomitant model class.
Objects can be created by calls of the form new("FLXP", ...),
typically inside driver functions like FLXPconstant or
FLXPmultinom.
name:Character string used in print methods.
formula:Formula describing the model.
x:Model matrix.
fit:Function returning the fitted prior probabilities.
refit:Function returning the fitted concomitant model.
coef:Matrix containing the fitted parameters.
df:Function for determining the number of degrees of freedom used.
Friedrich Leisch and Bettina Gruen