Standard Deviation & Variance (Edexcel A-Level Mathematics): Quizzes

Average deviation of data from the mean

Squared spread of data

$\sigma = \sqrt{\sigma^2}$

$\sigma^2 = \frac{\Sigma (x - \bar{x})^2}{n}$

$\sigma^2 = \overline{x^2} - (\bar{x})^2$

The mean of all squared data

The mean of all data then squared

To make the deviations positive

Standard deviation

Range

Interquartile range

When the highest value is unknown