[R] Question about predict.glm

[Prof Brian D Ripley]

On Sat, 8 Jul 2000 brian_adams at jbadams.com wrote:

> I am trying to use predict.glm to validate a logistic model.  Using
> 
> predictions <- predict.glm(logit.model, type="response",
> dataframe="validate")
> 
> I get the predictions from the original dataframe, not the validation
> data frame.  Am I missing an input to the method or is this what is
> supposed to happen?

The argument is `newdata'.  ?predict.glm seems clear enough to me
(but then I wrote it).


Usage:

     predict.glm(object, newdata = NULL, type = c("link", "response", 
"terms"),
                 se.fit = FALSE, dispersion = NULL, terms = NULL, ...)

Arguments:

  object: a fitted object of class inheriting from `"glm"'.

 newdata: optionally, a new data frame from which to make the
          predictions.  If omitted, the fitted linear predictors are
          used.

so I think it is working as documented ....

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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