Misunderstanding the summation formula

[averygoodmann]

Dear people,

I am managing to misunderstand a basic summation formula. In the picture attached I am showing an example of how I am solving an equation with 2 numbers (X1=2, X2=3)
A program gives results, that I am showing in the second picture, which are different: sigma squared = 0.25; I get 0.5 - means I dont understand the basic summation formula. I need to understand how it works. Would someone be able to write the correct expression/solution?

Thank you so much....

 

[Deleted member 4993]

Dear people,

I am managing to misunderstand a basic summation formula. In the picture attached I am showing an example of how I am solving an equation with 2 numbers (X1=2, X2=3)
A program gives results, that I am showing in the second picture, which are different: sigma squared = 0.25; I get 0.5 - means I dont understand the basic summation formula. I need to understand how it works. Would someone be able to write the correct expression/solution?

Thank you so much....

You did NOT misunderstand the summation formula.

The formula provided is in correct! It should be:

\(\displaystyle {\sigma}^2 = \frac{\sum{(X_{median} - X)^2}}{N}\)

So you have to divide the sum ( = 0.5 in this case) by number of observations ( = 2 in this case) to get the correct value of \(\displaystyle {\sigma}^2\) ( = 0.25 in this case)

 

[averygoodmann]

Awesome! That's good news! Thank you Mr. Khan!