This is a generic method. Unlike model.frame and model.matrix, this does not return transformed variables. It deals with regression formulae that have functions like poly(x, d) in them. It differentiates x from d in those expressions. And it also manages log(x + 10). The default method works for standarad R regression models like lm and glm.
model.data(model, ...)
A fitted regression model in which the data argument is specified. This function will fail if the model was not fit with the data option.
Arguments passed to implementing methods.
A data frame