This is how we assigned values for each statistic:
"The second sample character, PC2, has well-balanced NADs, with only one bad defense and a starting ability array of 16, 16, 12, 12 (pre-racials). This character would have racial bonuses to both primary and secondary abilities, and a +2 class bonus to the best defense, for starting NAD scores of 16, 14, and 11 (from best to worst defense). This character could be a Whirling Barbarian or a Chaos Sorcerer, among others."
This graph shows the Survivability progression for attacks against AC: