Manipulating the sample variance formula

**incblue** · June 18th 2011, 05:03 AM

Hello.

I am trying to prove the identity in red. (My failed attempt is in black)

**Archie Meade** · June 18th 2011, 05:12 AM

Originally Posted by incblue

Hello.

I am trying to prove the identity in red. (My failed attempt is in black)

If you multiply out the numerator of the red LHS,
then use the fact that

$\sum{x_i}=n(mean)$

the result follows.

**incblue** · June 18th 2011, 05:29 AM

Originally Posted by Archie Meade

If you multiply out the numerator of the red LHS,
then use the fact that

$\sum{x_i}=n(mean)$

the result follows.

Thanks, it was easy after applying that.

Thread: Manipulating the sample variance formula