[Rd] inaccuracy in qbinom with partial argument matching
Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri Jun 29 08:03:32 CEST 2007
On Thu, 28 Jun 2007, Peter Ruckdeschel wrote:
> I found the following strange effect with
> qbinom & partial argument matching
> p0 <- pbinom(0, size = 3, prob = 0.25)
> qbinom(p0, size = 3, prob = 0.25) ## 0 o.k.
> qbinom(p0-0.05, size = 3, prob = 0.25) ## 0 o.k.
> ## positional matching:
> qbinom(p0, 3, 0.25) ## 0 o.k.
> ## partial argument matching:
> qbinom(p0 , s = 3, p = 0.25) ## 1 ???
> qbinom(p0-0.05, s = 3, p = 0.25) ## 1 ???
> qbinom(p0-0.06, s = 3, p = 0.25) ## 0 o.K.
> Unfortunately I have no I idea how to fix this.
You use a call that specifies your intentions accurately. This is not
'partial argument matching': 'p' is an exact match to the first argument
function (p, size, prob, lower.tail = TRUE, log.p = FALSE)
and that is how argument matching in R is documented to work.
The 'inaccuracy' is in the diagnosis: please see the FAQ.
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 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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