!$ \widehat{ \sigma}^2 = { \large \sum_{i =1}^n ( x_i - \bar{x})^2 \over n -1} !$ e !$ s^2= { \large sum_{i =1}^n ( x_i - \bar{x})^2 \over n} !$

!$ \widehat{ \sigma}^2 = { \large \sum_{i =1}^n (x_i)^2 \over n} !$ e !$ s^2= { \large sum_{i =1}^n ( x_i )^2 \over n -1} !$

!$ \widehat{ \sigma}^2 = { \large \sum_{i =1}^n ( \bar{x})^2 \over n -1} !$ e !$ s^2= { \large sum_{i =1}^n ( \bar{x})^2 \over n} !$

!$ \widehat{ \sigma}^2 = { \large \sum_{i =1}^n ( x_i - \bar{x})^2 \over n} !$ e !$ s^2= { \large sum_{i =1}^n ( x_i - \bar{x})^2 \over n -1} !$

!$ \widehat{ \sigma}^2 = { \large \sum_{i =1}^n ( \bar{x})^2 \over n -1} !$ e !$ s^2= { \large sum_{i =1}^n (\bar{x})^2 \over n -2} !$