Standard Deviation (Leaving Cert Mathematics): Flashcards

Spread/variation in data from the mean

Data clustered close to the mean

Data spread out over wider range

$\sigma$ (sigma)

68%

95%

99.7%

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

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

Calculate the mean $(\bar{x})$

Square each deviation

No, it cannot be negative