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EWMACHART Statement |

See MACEW3 in the SAS/QC Sample Library |

The upper (lower) control limits in Output 20.1.1 are monotonically increasing (decreasing). As the number of subgroups increases, the control limits approach the following asymptotic values:

These constant limits are displayed if you specify the ASYMPTOTIC option,
as illustrated by the following statements:

title 'Constant Control Limits Based on Asymptotic Values'; symbol v=dot c=salmon; proc macontrol data=clips1; ewmachart gap*day / mu0 = 15 sigma0 = 0.2 weight = 0.3 xsymbol = mu0 asymptotic cframe = vibg cinfill = ligr coutfill = yellow cconnect = salmon; run;

The chart is shown in Output 20.2.1.

Note that the same three points that were outside the exact limits (displayed in Output 20.1.1) fall outside the asymptotic limits. The exact limits quickly approach the asymptotic values, so only the first few subgroups have appreciably different limits.

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