[R] Variance of a single number

[Petr Pikal]

Most probably:


     The denominator n - 1 is used which gives an unbiased 
estimator of
     the (co)variance for i.i.d. observations. These functions return
     `NA' when there is only one observation (whereas S-plus has 
been
     returning `NaN'), and from R 1.2.3 fail if `x' has length zero.

from help page for var

try
?var


On 10 Dec 2002 at 15:50, Adaikalavan Ramasamy wrote:

> Just out of curiosity, can some please explain the following return
> NA.
> 
> x <- 6
> var(x)
> 
> y <- c( NA, NA, 10000 )
> var(y, na.rm=T)
> 
> 
> Unless I am seriously misguided, I believe that the variance of a
> single number (i.e. a constant) should be zero. Thanks.
> 
> Regards, Adai.
> 
> ______________________________________________
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Petr Pikal
petr.pikal at precheza.cz
p.pik at volny.cz