At 10:10 AM -0500 9/23/00, Stuart Mckelvie wrote:
>Dear Tipsters,
>
>One reason we use the standard deviation is that it comes from the
>family of functions called moments about the origin of the
>distribution:
>
>Moment (r) = E[(X - mean) to power r]
>
>(sorry that the program does not give proper symbols)
>
>So the first moment = E[X - mean] = E(x) - E(mean) = mean -mean = 0
>
>The second momen = E[(X - mean)squared] = variance
>
>The third mean reflect symmetry or skewness.
This is probably the best answer yet.
In physics, the first, second and third moments (I think; my reference is
in my office and I'm not) correspond to frequency, rate and acceleration.
* PAUL K. BRANDON [EMAIL PROTECTED] *
* Psychology Department 507-389-6217 *
* "The University formerly known as Mankato State" *
* http://www.mankato.msus.edu/dept/psych/welcome.html *
