Re: [R] two-tailed exact binomail test
Peter Dalgaard wrote:
>katrina smith <[EMAIL PROTECTED]> writes:
>
>
>
>>I am trying to find a definition for the two-tailed exact binomial
>>test but have been unsuccessful. Can you help?
>>
>>
>
>Just read binom.test. The relevant bit is this:
>(m is the mean == n*p)
>
>else if (x < m) {
>i <- seq(from = ceiling(m), to = n)
>y <- sum(dbinom(i, n, p) <= d * relErr)
>pbinom(x, n, p) + pbinom(n - y, n, p, lower = FALSE)
>}
>
>i.e. we take the lower tail, including the value observed + the part
>of the upper tail where the binomial density is less than or equal to
>that of x (with a little fuzz added in). Symmetrically for observations
>in the upper tail of course.
>
>If you were looking for an "official" definition of the two sided
>exact test, I don't think one exists. R's version is equivalent to the
>likelihood ratio test, but there are alternatives (tail-balancing,
>doubling the one-sided p, and maybe more).
>
>
>
there is a reference:
Section 2.4.2 ("Zweiseitige Tests in einparametrigen
Exponentialfamilien" - two sided tests in one-parameter exponential
families) in
H. Witting (1985): Mathematische Statistik I. Teubner. Stuttgart
confer Satz 2.70, Korollar 2.73 (in case of symmetry)
and Beispiel 2.74 (application of Korollar 2.73 to binomial model for p=
0.5).
Matthias
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Re: [R] two-tailed exact binomail test
katrina smith <[EMAIL PROTECTED]> writes:
> I am trying to find a definition for the two-tailed exact binomial
> test but have been unsuccessful. Can you help?
Just read binom.test. The relevant bit is this:
(m is the mean == n*p)
else if (x < m) {
i <- seq(from = ceiling(m), to = n)
y <- sum(dbinom(i, n, p) <= d * relErr)
pbinom(x, n, p) + pbinom(n - y, n, p, lower = FALSE)
}
i.e. we take the lower tail, including the value observed + the part
of the upper tail where the binomial density is less than or equal to
that of x (with a little fuzz added in). Symmetrically for observations
in the upper tail of course.
If you were looking for an "official" definition of the two sided
exact test, I don't think one exists. R's version is equivalent to the
likelihood ratio test, but there are alternatives (tail-balancing,
doubling the one-sided p, and maybe more).
--
O__ Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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Re: [R] two-tailed exact binomail test
You might find the answer in Chapter 2 of Nonparametric statistical methods written by Myles Hollander and Douglas A. Wolfe (2nd ed., ISBN: 0-471-19045-4) 2005/8/27, katrina smith <[EMAIL PROTECTED]>: > I am trying to find a definition for the two-tailed exact binomial test but > have been unsuccessful. Can you help? > > > > > - > > [[alternative HTML version deleted]] > > __ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
[R] two-tailed exact binomail test
I am trying to find a definition for the two-tailed exact binomial test but have been unsuccessful. Can you help? - [[alternative HTML version deleted]] __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
