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Kendall's tau

5 messages · Martin Henry H. Stevens, Peter Dalgaard, Brian Ripley +2 more

Original
Martin Henry H. Stevens
# 
A search of the archives did not reveal an answer:
For basic tests of association, where one has no a priori knowledge of the 
form of the relation or of the distributions of the variables, rank 
correlation seems like a good start. Why is cor.test() with Kendall and 
Spearman options relegated to the ctest package, rather than in the base 
package? Does this suggest that the developers consider other tests of 
association more generally useful?
Thanks,
Hank

Martin Henry H. Stevens, Assistant Professor
338 Pearson Hall
Botany Department
Miami University
Oxford, OH 45056

Tel: (513) 529-4206
FAX: (513) 529-4243
http://www.muohio.edu/~botcwis/bot/henry.html

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Peter Dalgaard
# 
"Martin Henry H. Stevens" <HStevens at muohio.edu> writes:
No. *All* "classical tests" are in ctest. Also t.test for instance.
Arguably other stuff (e.g. lm/glm) ought to be moved away from base
and automatically loaded upon startup in the same way that ctest is,
leaving a "lean, mean, and clean" core, that could be used efficiently
in e.g. shell scripts. (R has a start-up time of about a second on
current hardware - give or take a few powers of 2, which is generally
tolerable unless running in a loop.)
Brian Ripley
#
On Thu, 25 Apr 2002, Martin Henry H. Stevens wrote:

            

      
      
      
    

        
It's *not* relegated.  t.test is there too!

There is no sense in which material in the standard or recommended
packages is not considered `generally useful'.  However, R does keep all
its code in memory, and the long-term aim has been to strip the base
package down to the bare essentials (e.g. removing lm).  Many R users
never use lm nor cor.test, and I suspect the vast majority of R sessions
do not use either.  If we had all the standard material in base, R would
run slower and need more memory (and the latter has been an issue until
recently, with 16Mb teaching labs).

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Jonathan Baron
    

    

      
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On 04/25/02 05:20, Martin Henry H. Stevens wrote:

            

      
      
      
    

        
I think I remember a version of R in which the ctest package had
to be loaded with library(), but it was a long time ago.
Everything in the ctest package is now simply available when you
start R.  I suspect that it is separate from "base" for
historical reasons.  It isn't clear to me whether change is
needed, and, if so, whether the base package should become even
larger or whether it should be broken up into yet more parts.  As
things are now, even on a fast computer loading from its own
disk, the html listing of the base package takes a bit of time to
load.  My own opinion is that this is a low-priority issue.

As for what to do when you don't know what your data look like,
my own recommendation is not to do anything in cor.test(), but,
use plot(), and then figure out what to do next, e.g., fix
errors, apply a tranform, or do a test.  Sometimes, of course,
you know in advance that tau is the appropriate test.

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Kjetil Halvorsen
    

    

      
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Brian Ripley wrote:

        
....
..
...
R would

            

      
      
      
    

        
We will have 8MB teaching labs for a long time still.

Kjetil Halvorsen

            

      
      
      
    

        
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