-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf Of Joe
Sent: Tuesday, March 19, 2002 11:41 AM
To: [EMAIL PROTECTED]
Subject: Coef. of skewness - Is my prof. crazy?
I'm taking an undergrad business stat. course. The prof. gave us a formula
to calculate the coefficient of skewness:
3(mean - median)/(std. dev )
And told us that the formula that excel uses to calculate skewness is
different/wrong.
I did a little digging to try and understand why Excel would use a
non-standard formula. The only equation that I found which came close to
what my prof. offered up was Pearson's second coef. of skewness which is:
3[mean] - [median] / (std. dev.)
Two questions, is the formula my prof. gave me valid, and why wouldn't I
use the Excel calculation for skewness? Is the formula I was given more
applicable to business statistics than what Excel uses?
Thanks for helping the statistcally insignificant.
-Joe
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This is Pearson's historical recommendations, proposed back in 1895. Fisher
changed things, and now we measure skewness using Fisher's method. The Excel
method is the correct Univariate way. Mardia's method is the correct
multivariate way. I have a full paper on the univariate ways, and can send
it as an attachment if anyone is interested.
DAHeiser
.
.
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