

   EExxttrraaccttiinngg tthhee ````EEnnvviirroonnmmeenntt'''' ooff aa MMooddeell FFoorrmmuullaa

        model.frame(formula, data, na.action, ...)
        model.frame.default(formula, data=sys.frame(sys.parent()),
                            na.action = na.fail, ...)

        Methods for
             lm   glm  aovlist

   AArrgguummeennttss::

    formula: a model formula

       data: `data.frame' or `environment' where the objects in
             formula are.

   na.action: how `NA's are treated.

        ...: further arguments such as.......

   DDeessccrriippttiioonn::

        `model.frame' (generic function) and its methods return
        a `data.frame' with the variables from `formula'.

   VVaalluuee::

        A `data.frame' containing the variables used in `for-
        mula'.

   SSeeee AAllssoo::

        `model.matrix' for the ``design matrix''.

   EExxaammpplleess::

        data(cars)
        data.class(model.frame(dist ~ speed, data = cars))

