The Range Method is a method
for estimating the standard
deviation that is used in Statistical
Process Control and Measurement
Systems Analysis. It uses the
equation:
s 
process standard deviation 

mean of the ranges
of a number of samples 
d_{2} 
a constant obtained from tables 
Normally 30 or more samples
should be used. Some of the methods used
in Measurement Systems Analysis use 15 samples
or less and in this case the equation is
modified to:
