Yes, the author of the message does :)
Your fit is exactly collinear. From ?predict.lm
If the fit is rank-deficient, some of the columns of the design
matrix will have been dropped. Prediction from such a fit only
makes sense if 'newdata' is contained in the same subspace as the
original data. That cannot be checked accurately, so a warning is
issued.
(in fact predict.lm is being called here.)
On Tue, 28 Mar 2006, stephenc wrote:
> Hi
>
> Does anyone know what this means:
>
>
>> glm.model = glm(formula = as.factor(nextDay) ~ ., family=binomial,
> data=spi[1:1000,])
>> pred <- predict(glm.model, spi[1001:1250,-9],
type="response")
> Warning message:
> prediction from a rank-deficient fit may be misleading in:
> predict.lm(object, newdata, se.fit, scale = 1, type = ifelse(type =>
> 9 is my determinant and I still get this message even when I remove the
> 9.
>
> Stephen
>
>
> [[alternative HTML version deleted]]
>
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--
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)
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