## Quick Reference

A measure of the dispersion of data in statistics. For a set of values *a*_{1}, *a*_{2}, *a*_{3}, … *a _{n}*, the mean

*m*is given by (

*a*

_{1}+

*a*

_{2}+ … +

*a*)/

_{n}*n*. The deviation of each value is the absolute value of the difference from the mean #|

*m*–

*a*

_{1}#|, etc. The standard deviation is the square root of the mean of the squares of these values, i.e. √[(#|

*m*–

*a*

_{1}#|

^{2}+ … #|

*m*–

*a*#|

_{n}^{2})/

*n*]

*Subjects:*
Science and Mathematics.

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