[R] Discriminant analysis

[Marc R. Feldesman]

At 11:59 PM 8/4/2005, C NL wrote:
 >Hi,
 >
 >  I'm a newbie in R and don't much aobut all the
 >modules and their capabilities, but I'm interested in
 >solving a problem about a discriminant analysis done
 >with SPSS tool. The thing is that I would like to make
 >a discrimant analysis similar to the one done with
 >SPSS, but I can't find the way to solve it.
 >
 >  I've been playing with R and I can handle more or
 >less my data, the point is that I need to know what
 >kind of discriminant analysis should I use to obtain
 >the same results as I obtain with SPSS. Should I use
 >"qda" or "lda"?? If not, what else could I use??
 >
 >  Can anybody help me to find out a light in my way?
 >I've been searching all over the web to fetch any help
 >or example but I couldn't get anything.
 >
 >  I would apreciate any help greatly.


If you're using R, you are not going to get "SPSS results" using lda or 
qda.  You will get results comparable to SPSS, but not all the extra 
output.  Virtually all the extra output can be obtained by taking advantage 
of the programming tools available to you in R.  What you should do is to 
learn what lda is capable of doing -- read the help files in particular, 
read the book(s) on which lda is based (MASS - "Modern Applied Statistics 
with S" by Venables and Ripley, as well as Ripley's "Pattern Recognition 
and Neural Networks". )  Both books - coupled with the help files and the 
examples - give you a pretty good sense of what you can do with lda.  Study 
the output of an lda object to see what is in there.  If you understand 
discriminant analysis and the computations involved, R provides all the 
tools to go from the lda object to most of the information that you 
want.  However, if you are looking for statistics at the push of a button, 
then I suggest you stick with SPSS or SAS (or as an alternative, the 
commercial version of S - SPlus, which does have a very powerful 
discriminant routine built on the top of lda).

Hope this helps.