Standard deviation is an index of variability that statisticians can use to characterize the dispersion among the measures in a given population. It’s the measure of the spread of the data about the mean. Numerically, the standard deviation is the square root of the variance. Unlike the variance, which is a somewhat abstract measure of variability, the standard deviation can be readily conceptualized as a distance along the scale of measurement. (see for a good non-technical explanation of Standard Deviation)

Other Definitions

Standard Deviation – The standard deviation of a probability distribution is defined as the square root of the variance (

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J. Jerrald Hayes
I am ex-architectural woodworker and general contractor turned IT, Business and Project Management consultant, software developer wannabe senior division triathlete and ski racer, Yankee fan and founder of, 360 Difference, and now too.
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