Re: [R] Discriminant Function Analysis

From: michael watson (IAH-C) <michael.watson_at_bbsrc.ac.uk>
Date: Thu 07 Jul 2005 - 18:58:04 EST


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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