[R] Discriminant Function Analysis
michael watson (IAH-C)
michael.watson at bbsrc.ac.uk
Thu Jul 7 10:58:04 CEST 2005
Thanks for the answers Uwe!
So this is a common problem in biology - few number of cases and many,
many variables (genes, proteins, metabolites, etc etc)!
Under these conditions, is discriminant function analysis not an ideal
method to use then? Are there alternatives?
> 1) First problem, I got this error message:
>>z <- lda(C0GRP_NA ~ ., dpi30)
> Warning message:
> variables are collinear in: lda.default(x, grouping, ...)
> I guess this is not a good thing, however, I *did* get a result and it
> discriminated perfectly between my groups. Can anyone explain what
> this means? Does it invalidate my results?
Well, 14 cases and 37 variables mean that not that many degrees of
freedom are left.... ;-)
Of course, you get a perfect fit - with arbitrary data.
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