[R] predict.lda posteriors equal to 1

Bill.Venables at csiro.au Bill.Venables at csiro.au
Sun Apr 12 03:48:06 CEST 2009


If you try

library(MASS)
example(lda)
predict(z)$posterior

You will see there are very many posterior probabilities there, too, which differe from 1 by round-off error at most.  So your data are not unique.

I don't get why you don't get it. 


Bill Venables
http://www.cmis.csiro.au/bill.venables/ 


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of gcam032
Sent: Sunday, 12 April 2009 11:16 AM
To: r-help at r-project.org
Subject: [R] predict.lda posteriors equal to 1


Hi all,

I was wondering if anyone was able to explain to me why when I run
predict.lda() on some new data I get lots of posterior probabilities = 1. 
This seems markedly unrealistic.  What do the posteriors mean in the context
of the predict.lda() function?

Thanks

Gareth
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