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EWMA
Control Limits
The upper & lower control
limits for the EWMA statistic :
where zo is the Starting
value (user defined as either the Target value or process mean value), n
is the subgroup size, d2 is a function of n (available in any statistical
quality control textbook), and m is the number of subgroups selected for
analysis.
The Range chart (n>1)
or the Moving Range chart (n=1) is generally used to monitor the process
variation.
See also:
Interpreting
an EWMA Chart
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