[Rd] variance of a scalar (PR#546)
Fri, 19 May 2000 09:57:10 +0100 (BST)
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
Jonathan Rougier Science Laboratories
Department of Mathematical Sciences South Road
University of Durham Durham DH1 3LE
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