[bbartlog]

For your example, in your data the average is -3.318.

412 * (2 - 3.318)^2 = 715.7
307 * (4 - 3.318)^2 = 142.8
211 * (6 - 3.318)^2 = 1517.7
70 * (0 - 3.318)^2 = 770.6

(715.7 + 142.8 + 1517.7 + 770.6) / 999 = 3.15