[R] binom.test

Francisco J. Zagmutt
Thu, 19 Oct 2006 16:27:08 -0000

You can also plot an uncertainty distribution of p, using an uninformed
prior (uniform(0,1)), using beta(s+1, n-s+1)  i.e.

x <- seq(0.091, 0.469, length=100)
plot(x, dbeta(.x, shape1=13, shape2=39), xlab="x",
ylab="Density",
main="Uncertainy distribution for p: beta(a = 12+1, b = 50-12+1)",
type="l")

Cheers,

Francisco


Dr. Francisco J. Zagmutt
College of Veterinary Medicine and Biomedical Sciences
Colorado State University



>From: Chuck Cleland <ccleland at optonline.net>
>To: Ethan Johnsons <ethan.johnsons at gmail.com>
>CC: r-help at stat.math.ethz.ch
>Subject: Re: [R] binom.test
>Date: Thu, 19 Oct 2006 11:27:35 -0400
>
>Ethan Johnsons wrote:
> > R-experts:
> >
> > A quick question, please.
> >
> >>From a lab exp, I got 12 positives out of 50.
> > To get 90% CI for this , I think binom.test might be the one to be
used.
> > Is there a better way or function to calculate this?
> >
> >> binom.test(x=12, n=50, p=12/50, conf.level = 0.90)
> >
> >         Exact binomial test
> >
> > data:  12 and 50
> > number of successes = 12, number of trials = 50, p-value = 1
> > alternative hypothesis: true probability of success is not equal to
0.24
> > 90 percent confidence interval:
> >  0.1447182 0.3596557
> > sample estimates:
> > probability of success
> >                   0.24
>
>You might consider binconf() in the Hmisc package too:
>
>library(Hmisc)
>binconf(12, 50, method="all")
>            PointEst    Lower    Upper
>Exact          0.24 0.130610 0.381691
>Wilson         0.24 0.142974 0.374127
>Asymptotic     0.24 0.121621 0.358379
>
> > thx much
> >
> > ej
> >
> > ______________________________________________
> > R-help at 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
> > and provide commented, minimal, self-contained, reproducible code.
>
>--
>Chuck Cleland, Ph.D.
>NDRI, Inc.
>71 West 23rd Street, 8th floor
>New York, NY 10010
>tel: (212) 845-4495 (Tu, Th)
>tel: (732) 512-0171 (M, W, F)
>fax: (917) 438-0894
>
>______________________________________________
>R-help at 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
>and provide commented, minimal, self-contained, reproducible code.

_________________________________________________________________
Stay in touch with old friends and meet new ones with Windows Live Spaces