Revision Date: 2005-09-08
Problem:
Control limits do not appear to line up or match the desired scale.
Solution:
1.
Make sure that the moving average in Type matches the set n in Limits.
A. In the Variables Control Charts window, select Modify.
B. Select Type.
C. Note the value in the Subgroups in moving average field.
D. Select Limits.
E. Select Create New Limits.
F. If the value in the Moving Average field matches the one in the Subgroups in moving average field, proceed to Step 2. If the values do not match, the discrepancy has caused your chart not to match the desired scale. Reconcile the two values.
2. Another reason for the chart to appear not to match may be that data is missing.
A. In the Groups window, select Enter Data.
B. If you are working with a subgroup size greater than one, examine the data for incomplete rows.
C. If any rows are incomplete, modify the subgroup size by selecting Modify Group.
D. Select Modify, then follow instructions to make a backup copy of your database.
E. In the Subgroup size field, enter a smaller value that allows each row to be complete.
Ref # 305
