R help - Sep 2013 - Hmisc binconf function value interpretation during narrow confidence intervals

Hello all,
I've been using binconf (package Hmisc) at a range of alpha values and
noticed that using the 'Wilson' method when alpha is larger (i.e. narrow
CI), results in the upper value being smaller than the lower value. The
'exact' and 'asymptotic' methods give results in the realm
I'd expect.
But the help file suggests:
"Following Agresti and Coull, the Wilson interval is to be preferred and
so is the default."

Suggestions and clarifications gratefully received.

The following code shows the curious results:

#calc 5% CI's.
require(Hmisc)
alpha <-.95
bin.prob <- binconf(1, 100, alpha=alpha,method='all')
colnames(bin.prob)[-1] <-
paste('p',c(alpha/2,1-alpha/2),sep='')
bin.prob

______________________________________
Michael Folkes
Salmon Stock Assessment
Canadian Dept. of Fisheries & Oceans     
Pacific Biological Station
3190 Hammond Bay Rd.
Nanaimo, B.C., Canada
V9T-6N7
Michael.Folkes at dfo-mpo.gc.ca

Hello,

Are you sure of the alpha value?

Regards,
Pascal


2013/9/10 Folkes, Michael <Michael.Folkes@dfo-mpo.gc.ca>
> Hello all,
> I've been using binconf (package Hmisc) at a range of alpha values and
> noticed that using the 'Wilson' method when alpha is larger (i.e.
narrow
> CI), results in the upper value being smaller than the lower value. The
> 'exact' and 'asymptotic' methods give results in the realm
I'd expect.
> But the help file suggests:
> "Following Agresti and Coull, the Wilson interval is to be preferred
and
> so is the default."
>
> Suggestions and clarifications gratefully received.
>
> The following code shows the curious results:
>
> #calc 5% CI's.
> require(Hmisc)
> alpha <-.95
> bin.prob <- binconf(1, 100, alpha=alpha,method='all')
> colnames(bin.prob)[-1] <-
paste('p',c(alpha/2,1-alpha/2),sep='')
> bin.prob
>
> ______________________________________
> Michael Folkes
> Salmon Stock Assessment
> Canadian Dept. of Fisheries & Oceans
> Pacific Biological Station
> 3190 Hammond Bay Rd.
> Nanaimo, B.C., Canada
> V9T-6N7
> Michael.Folkes@dfo-mpo.gc.ca
>
> ______________________________________________
> R-help@r-project.org 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.
>


-- 
Pascal Oettli
Project Scientist
JAMSTEC
Yokohama, Japan

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