Hi;
I know the formula for variance and that a low value means the data is more compact
and a larger value means spread out more.
But what does the value actually relate to?
It is a measure of spread
for more details look here..:
Variance - Wikipedia, the free encyclopedia
The average of several numbers which have been squared is not equal to the average of the numbers then squared.
Suppose you have 2 numbers a and b
The average of their squares is $\displaystyle \frac{a^2+b^2}{2}$
The square of their average is $\displaystyle (\frac{a+b}{2})^2=\frac{a^2+2ab+b^2}{4}$
You can see that they are different values.