[R] Different results in calculating SD of 2 numbers

Martin Maechler maechler at stat.math.ethz.ch
Wed Jan 16 09:45:04 CET 2008


>>>>> "RM" == Ron Michael <ron_michael70 at yahoo.com>
>>>>>     on Wed, 16 Jan 2008 00:14:56 -0800 (PST) writes:

    RM> Hi all,
    RM> Can anyone tell me why I am getting different results in calculating SD of 2 numbers ?

    >> (1.25-0.95)/2
    RM> [1] 0.15
    >> sd(c(1.25, 0.95))
    RM> [1] 0.2121320          # why it is different from 0.15?

because  1 is different from 2 !
If 2 was 1, than sqrt(2) == 1 as well, but actually I don't
think the universe and we all would exist in that case ....

Martin Maechler, ETH




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