Re: [R] Reconstructing LD function

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Mon 27 Jun 2005 - 21:18:16 EST

On Mon, 27 Jun 2005 usenet@s-boehringer.de wrote:

> in an LDA analysis with n groups n-1 LD functions result. Implicitly this
> defines an LD fucntion for the last group. Does there exist code already
> to explictly construct this LD function?

What `LDA analysis' are our discussing here? (LDA is usually `linear discriminant analysis', so what did you mean and what R function are you nor referring to?)

R has lda in package MASS, and that works with n LD functions. To reduce it to n-1, subtract the last one from the others, in which case LD_n == 0.

Anything you do in LD analysis only depends on differences in LD functions, and there really are n of them. With two groups one is conventionally taken to be zero (the first, usually, not the last).

-- 
Brian D. Ripley,                  ripley@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

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Received on Mon Jun 27 21:22:38 2005

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