Statistics & Probability
\( \displaystyle \sum_{i=1}^n (x_i - \bar x)^2 = \displaystyle \sum_{i=1}^n x_i^2 - n \bar x^2 \)
\( s^2 = \displaystyle \sum_{i=1}^n \frac{(x_i - \bar x)^2}{n} = \frac{\displaystyle \sum_{i=1}^n x_i^2}{n} - \bar x^2 \)
NCEE
\( \displaystyle \sum_{i=1}^n (x_i - \bar x)^2 = \displaystyle \sum_{i=1}^n x_i^2 - n \bar x^2 \)
\( s^2 = \displaystyle \sum_{i=1}^n \frac{(x_i - \bar x)^2}{n} = \frac{\displaystyle \sum_{i=1}^n x_i^2}{n} - \bar x^2 \)