[R] Strange predicted values ?

[Prof Brian Ripley]

Let me remind you that originally you did not understand why the fitted
values did not match up with some other set of values of var1 to var4 you
cbind-ed.  You need to predict at those values for what *you* did not to
be `strange'.

Please do as I suggested and consult the documentation. 


On Thu, 7 Aug 2003, orkun wrote:

> Prof Brian Ripley wrote:
> 
> >On Thu, 7 Aug 2003, orkun wrote:
> >
> >[quoting me without attribution]
> >
> >  
> >
> >>>Those are not predicted values, they are fitted values.  Try predicting on 
> >>>the same set of variables as you printed.
> >>>      
> >>>
> >
> >Precisely!  From ?predict.glm
> >
> > newdata: optionally, a new data frame from which to make the
> >          predictions.  If omitted, the fitted linear predictors are
> >          used.
> >
> >[...]
> >
> >  
> >
> >>If  predict(glm.obj,type="resp") does not give predicted vals, How can I 
> >>get predicted values ?
> >>    
> >>
> >
> >Try reading the help page?  It is quite explicit, and has examples, as do 
> >all good books on S/R.
> >
> >  
> >
> I tried this:
> #I think since an interaction exists in glm.obj, data.frame.obj did not 
> not work
> #instead I used model.frame obj (it works)
> newdata<-model.frame(glm.obj)
> pr<-predict.glm(glm.obj,newdata,type="resp")
> it works but there was a warning message:
> prediction from a rank deficient fit may be misleading in predic.lm (....)
> 
> any suggestions ?

Follow advice when it is given to you.

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595