[R] 2 LDA

From: Steve Adams <steve_adams_sd_at_yahoo.com>
Date: Thu 16 Jun 2005 - 06:53:43 EST


Hi,

I am using Partek for LDA analysis. For a binary response variable, it generates 2 discriminant functions, one for each of the 2 levels of the response variable. And I can simply calculate 2 discriminant scores (say d1 and d2) for each sampples using the 2 discriminant functions, then I can use the following formula to compute the posterior probability for the sample:

p1=exp(d1-d2)/(1+exp(d1-d2))
p2=1/(1+exp(d1-d2))

In R, the lda function only generates 1 discriminant function, and exactly the same posterior probability as the LDA function in Partek does.

My question is what's the difference (or relationship) between the above 2 LDA functions, where I can find the reference for the partek LDA function?

Thanks

Steve



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