The following examples are taken from Wikipedia.

http://en.wikipedia.org/wiki/Standard_deviation

- >>> standard_deviation([0, 0, 14, 14])

- >>> standard_deviation([0, 6, 8, 14])

+ >>> standard_deviation([0, 0, 14, 14]) # doctest: +ELLIPSIS

+ >>> standard_deviation([0, 6, 8, 14]) # doctest: +ELLIPSIS

>>> standard_deviation([6, 6, 8, 8])

# Fictitious average monthly temperatures in Southern California.

# Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

- >>> standard_deviation([70, 70, 70, 75, 80, 85, 90, 95, 90, 80, 75, 70])

+ >>> standard_deviation([70, 70, 70, 75, 80, 85, 90, 95, 90, 80, 75, 70]) # doctest: +ELLIPSIS

# Fictitious average mothly temperatures in Montana.

# Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

- >>> standard_deviation([-32, -10, 20, 30, 60, 90, 100, 80, 60, 30, 10, -32])

+ >>> standard_deviation([-32, -10, 20, 30, 60, 90, 100, 80, 60, 30, 10, -32]) # doctest: +ELLIPSIS

Most natural and random phenomena follow the normal distribution (aka the

bell curve), which says that most values are close to average but a few are

+ >>> stats.mean # doctest: +ELLIPSIS

>>> stats.standard_deviation