Variability statistics

Question

Calculate SS (sum of squares), variance, and standard deviation for the following population of scores: 8,1,4,3,5,3,4.

Answer 1

8+1+4+3+5+3+4 = 28

n=7

28/7 = 4 = mean

8-4 = 4, 4^2 = 16

1-4 =-3 -3^2 = 9

4-4=0 0^2 = 0

3-4 = -1 -1^2 = 1

5-4 = 1 1^2 = 1

3-4 = -1 -1^2 = 1

4-4=0 0^2 = 0

sum of squares = SS = 16+9+0+1+1+1+0 = 28

variance = SS/n = 28/7 = 4

standard deviation = sqr(variance) = sqr4 = 2

because this is the population the formula uses n, not n-1