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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

I have revised the footnote "Why square the differences?" on the page Standard Deviation and Variance

Do you agree with the footnote?

Could it be better explained?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 102,350

Hi;

Those are all valid reasons. You could add that using the absolute value is harder to algebraically manipulate.

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,501

hi MathsIsFun,

That's pretty much what I say when I'm introducing this. It's interesting to watch a class would out the mean of the differences and then start scratching their heads. I think that practical drives the lesson home more effectively than anything and it improves their understanding of what a mean actually is.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,604

Thanks guys!

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 102,350

Hi;

Have you noticed that Wikipedia can save its pages in PDF format. So I save them and join them to make a nice book. Is that possible to make yours into PDF's?

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.** **A number by itself is useful, but it is far more useful to know how accurate or certain that number is.**

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