Referring your example:
variance = 2_nd moment - (1_st moment),
that is:
2_nd moment = 0^2 * 0.2 + 1^2 * 0.3 + 2^2 * 0.2 + 3^2 * 0.2 + 4^2 * 0.1 =
4.5
1_st moment = 0 * 0.2 + 1 * 0.3 + 2 * 0.2 + 3 * 0.2 + 4 * 0.1 = 1.7
then
variance = 4.5 - (1.7)^2 = 1.61
then
standard deviation = sqrt(1.61) = 1.27
bye Paolo (I hope that's right)
"Chris Chiu" <[EMAIL PROTECTED]> ha scritto nel messaggio
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Dear friends:
>
> Does anyone know / remember how to obtain the standard deviation of a set
> of numbers given only a frequency table?
>
> e.g.,
> x f(x)
> 0 0.2
> 1 0.3
> 2 0.2
> 3 0.2
> 4 0.1
>
> Many thanks.
> Chris
>
>
>
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