AW: [R] binom.test appropriate?
Prof Brian D Ripley
ripley at stats.ox.ac.uk
Sat Jun 9 09:04:59 CEST 2001
On Sat, 9 Jun 2001, [iso-8859-1] Lüdde Mirko wrote:
> 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 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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