[R] Kendall's tau

[ripley@stats.ox.ac.uk]

On Thu, 25 Apr 2002, Martin Henry H. Stevens wrote:

> 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?

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).

-- 
Brian D. Ripley,                  ripley at 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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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