I have ten measurements like this:
and I have calculated the sample mean E(X) = 10.03, and the average of squares E(X^2) = 100.679:
Now I want to calculate the sample variance. I use the formula:
sample variance = E(X^2) - (E(X))^2 = 100.679 - (10.03)^2 = 0.0781
However, when using a calculator to calculate the variance, it gives the result
variance = 0.08678 instead.
What did I do wrong?