AW: [R] binom.test appropriate?

Prof Brian D Ripley ripley at
Sat Jun 9 09:04:59 CEST 2001

On Sat, 9 Jun 2001, [iso-8859-1] Lüdde Mirko wrote:

> No,
> since I'd like to test
> 	null: p <= p0
> 	alternative: p > p0.
> and my understanding is that binom.test tests
> 	null: p = p0 (can only be a "simple" null hypothesis
> 			according to help(binom.test))
> 	alternative: p > p0 (or p < p0 or p != p0).

But: the test for p = p0 vs p > p0 is the appropriate test for
p <= p0 vs p > p0 within this family of tests, by the monotonicity

You mentioned a 2 x 2 table and UMPU, but did not say exactly what you are
doing or how the data were sampled, nor how this hypothesis arises.  Under
one set of assumptions, I believe the UMPU theory you mention tells you to
use the binom.test for p = p0 vs p > p0, but it may be that other tests
(Fisher's exact test springs to mind) are more appropriate.  (And the last
U can be insidious, just as it can be for estimation.)

It's rare to have hypotheses like p = p0 or p <= p0 with p0 known
precisely: Mendelian genetics provides almost all the examples I have ever
seen.  If p0 comes from past experience, then it's a different problem.


Brian D. Ripley,                  ripley at
Professor of Applied Statistics,
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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