Refers to the mean of the squares of the deviations from the mean. It is equivalent to the Variance and is calculated from:
See Mean Square Deviation
The difference between the largest and smallest value in a subgroup. It can be used to estimate the process standard deviation, see Range Method.
A method for estimating the standard deviation used in Statistical Process Control and Measurement Systems Analysis. It uses the formula:
where 's' is the process standard deviation, and is the mean of more than 15 (preferably 30) samples, each containing an equal number of items. The constant d_{2} is obtained from tables. If there are 15 samples, or less, then the formula is:
Root Mean Square Error, an alternative term for the standard deviation, calculated using the formula:
A measure of the dispersion of a data set. It can be calculated using the Range Method or the RMSE method.
A measure of the dispersion of a data set. The variance of a population is estimated from a sample using the formula:
