[Rd] variance of a scalar (PR#546)
Prof Brian Ripley
Prof Brian Ripley <firstname.lastname@example.org>
Fri, 19 May 2000 10:04:09 +0100 (BST)
> Date: Fri, 19 May 2000 09:57:10 +0100 (BST)
> From: Jonathan Rougier <J.C.Rougier@durham.ac.uk>
> To: Prof Brian Ripley <email@example.com>
> cc: firstname.lastname@example.org, Remail@example.com
> Subject: Re: [Rd] variance of a scalar (PR#546)
> On Fri, 19 May 2000, Prof Brian Ripley wrote:
> > > I was surprised to find that the variance of a scalar, using
> > > var(), is NA. Surely this should be zero?
> > >
> > Do you mean a vector of length 1? (S has no scalars.) No, it should be
> > NA, as sum((x-xbar)^2)/(n-1) is NaN, or, in statistical terms, one has
> > no idea at all of the variability from a single sample.
> I thought that might be the reason. There is no mention of using n-1
> rather than n in the denominator on the help page. Perhaps that might be
Um. What professional statistics package uses n, then? Are you
suggesting that there is serious room for doubt?
Brian D. Ripley, firstname.lastname@example.org
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
r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To: email@example.com