Using Basic Statistics

The set of basic statistics includes measures of central tendencies, measures of dispersion, and the other descriptive statistics, as shown in the following table:

Equation	Statistic	Alternate Equation Forms
	The mean is the arithmetic mean (average) of a sample.	See References.
	The standard deviation is the root-mean-square of a sample.	See References.
	The observation is the total number of values in a sample.	None
	The summation is the total of all the values in a sample.	None
	The minimum is the smallest value in the sample.	None
	The maximum is the largest value in the sample.	None
	The range is the largest value minus the smallest value in the sample.	None
	The variance is the square of the standard deviation.	See References.
	The standard error of the mean is the standard deviation of the mean. It measures the extent to which a sample mean can be expected to vary.	See References.
	The coefficient of variation is the standard deviation of a sample expressed as a percentage of the mean. It is a measure of relative dispersion.	See References.
	The lower Z-score is the number of standard deviations that the lower specification limit (LSL) is from the mean.	None
	The upper Z-score is the number of standard deviations that the upper specification limit (USL) is from the mean.	None
Lwr 3 sigma = deviate at probability 0.00135	The lower 3 sigma represents three standard deviations from left of the mean.	None
Upr 3 sigma = deviate at probability 0.99865	The upper 3 sigma represents three standard deviations from right of the mean.	None