Produces exponentially weighted moving average (EWMA) charts. The EWMA chart is a time-weighted control chart used to monitor the mean of a process, giving less weight to data as they get older. It is particularly effective for detecting small shifts in the process mean.
| Parameter | Description |
|---|---|
| allN | When set to True, includes all subgroups regardless of whether the subgroup sample size equals the nominal sample size. |
| asymptotic | When set to True, produces asymptotic control limits. |
| chartsTable | Specifies the charts summary output data table. |
| display | Specifies a list of results tables to send to the client for display. |
| exChart | When set to True, includes a control chart in the results only when exceptions occur. |
| groupByLimit | Suppresses the analysis if the number of groups exceeds the specified value. |
| limitN | Specifies a nominal sample size for the control limits. |
| limitsTable | Specifies the control limits data table. |
| outLimitsTable | Specifies the output control limits data table. |
| outputTables | Lists the names of results tables to save as CAS tables on the server. |
| processName | Specifies the variable in the input data table that contains the names of processes to be analyzed. |
| processValue | Specifies the variable in the input data table that contains the process measurements to be analyzed. |
| reset | When set to True, resets the value of the exponentially weighted moving average after each point outside the control limits. |
| sigmas | Specifies the width of the control limits as a multiple of the standard error of the subgroup summary statistic. |
| sMethod | Specifies the method of estimating the process standard deviation (RMSDF, SMVLUE, or SNOWEIGHT). |
| subgroupName | Specifies the variable in the input data table that contains the names of subgroup variables. |
| subgroupValue | Specifies the variable in the input data table that contains the subgroup values. |
| table | Specifies the settings for the input table. |
| weight | Specifies the weight (lambda) that is assigned to the most recent subgroup. The value must be between 0 and 1. |
Generates a dataset 'metalclips' containing gap measurements for metal clips produced over several days, to be used for process control analysis.
| 1 | |
| 2 | DATA mycas.metalclips; |
| 3 | INPUT day @; |
| 4 | DO i=1 to 5; |
| 5 | INPUT gap @; |
| 6 | OUTPUT; |
| 7 | END; |
| 8 | drop i; |
| 9 | DATALINES; |
| 10 | 1 14.98 15.02 14.99 15.01 15.00 2 15.01 14.99 15.00 15.02 15.01 3 15.03 15.00 15.01 15.02 15.00 4 14.99 15.01 15.00 14.98 15.02 ; |
| 11 | |
| 12 | RUN; |
| 13 |
Generates a basic EWMA chart using the gap measurements and day subgroups.
| 1 | |
| 2 | PROC CAS; |
| 3 | spc.ewmaChart / TABLE={name="metalclips", caslib="mycas"} processValue="gap" subgroupValue="day"; |
| 4 | |
| 5 | RUN; |
| 6 |
Generates an EWMA chart with a specific weight factor and sigma limit, saving the calculated control limits and chart summary to CAS tables.
| 1 | |
| 2 | PROC CAS; |
| 3 | spc.ewmaChart / TABLE={name="metalclips", caslib="mycas"} processValue="gap" subgroupValue="day" weight=0.2 sigmas=3 outLimitsTable={name="ewma_limits", caslib="mycas", replace=true} chartsTable={name="ewma_summary", caslib="mycas", replace=true}; |
| 4 | |
| 5 | RUN; |
| 6 |