## For the numbers 1, 2, and 3

- The mean is obviously 2, and
- s2 = (1-2)2 + (2-2)2 + (3-2)2 divided by 3 = 0.67

## But the scatter of 1 and 3 on either side of 2

- Is obviously 1.00. So, our answer has a bias
- Because it includes the mean value 2

- Is obviously 1.00. So, our answer has a bias

## So the realistic answer for variance

- Is given by the formula

s2 = S (x-M)2

N-1- Where M = Mean and N = Number of readings
- And S means "Sum of all"

- Is given by the formula

Previous slide | Next slide | Back to first slide | View graphic version |