Subgroups in control charts can be color and symbol coded based on specific values of the traceability fields. This is useful to investigate data stratification. For example, if you suspect that process output is different for material from Supplier A, you can color and/or symbol code the subgroups based on a Traceability field to identify the Supplier.
Alternatively, or in addition, you may wish to standardize the data based on particular values of a traceability field to construct Short Run SPC control charts. In this case, the process control chart may be used to analyze different parts or units having distinct nominal values, such as a drilling station that drills a different size hole for different part numbers, or a packaging operation that includes six screws for large units and only 4 screws for smaller units.
See also:
Standardized Observations : calculations used for standardizing the data for Short Run variables (X-Bar and Individual-X) charts.
Standardized P Statistic : calculations used for standardizing the data for Short Run P charts.
Standardized Np Statistic : calculations used for standardizing the data for Short Run Np charts.
Standardized U Statistic : calculations used for standardizing the data for Short Run U charts.
Standardized C Statistic : calculations used for standardizing the data for Short Run C charts.
The symbol criteria are displayed in the table whose columns read Traceability, Traceability Item, Mean, and Process Sigma.
· To add a new item, select the Add button to open the Define Standardization and Symbol dialog box.
· Select a Traceability Field (or the Subgroup Note item) from the list box at the left, then select one of the Traceability Items specific to the Traceability Field from the list box at the right.
· Select the <ANYTHING> item to include records where the selected Traceability Field is not empty.
· The Traceability Item for linked data must be entered exactly as entered in the ODBC source (no wildcard operators are permitted).
· To edit an item, select the item from the table, then select the Edit button to open the Define Standardization and Symbol dialog box for the current item.
· To delete an item, select the item from the table, then select the Remove button. This does not remove any data, only the symbol formatting or standardization associated with the data.
· Since items can meet more than one criterion, the order of the items in the list (top to bottom) establish precedence. Use the Up and Down buttons to move things in the list. Items lower in the list will not be applied if the subgroup also meets a condition higher in the list.
Show Symbols on Chart: Select this option to show the symbols. De-select this option to temporarily remove the symbols (return to black dots).