The standard deviation is a statistical measure of the dispersion or uncertainty in a random variable. The standard deviation is the square root of the variance, a measure of how spread out a distribution is, and is written for a random variable x as: = [^N_{i= 1}(x_i - x)²/N - 1], is the standard deviation, x_i is each individual value of x, is the mean of all of the data points, and N is the number of data points. In this form the standard deviation is an unbiased estimate of the variance and is sometimes said to be corrected for a loss of a degree of freedom. On occasion the standard deviation is written as a biased estimate of the variance when the denominator is just N rather than N - 1. The value of x_i - x is called the residual for each...