If you have multiple columns of process data, without a grouping variable, do the following:
Observations within each subgroup should be in adjacent rows of the worksheet. For more information on using columns to define subgroups, go to Using subgroups to assess process capability.
C1 | C2 |
---|---|
Diameter Shift 1 | Diameter Shift 2 |
74.030 | 73.992 |
74.002 | 74.014 |
74.019 | 73.887 |
If you have only one column of process data, and another column to indicate grouping information, do the following:
Observations within each subgroup should be in adjacent rows of the worksheet. For more information on using columns to define subgroups, go to Using subgroups to assess process capability.
C1 | C2 |
---|---|
Diameter | Shift |
74.030 | 1 |
74.002 | 1 |
74.019 | 1 |
73.992 | 2 |
74.014 | 2 |
73.887 | 2 |
To perform the analysis, you must enter a lower specification limit, an upper specification limit, or both.
Select to define a lower specification limit as a boundary only if it is not possible for measurements to fall below the Lower spec value. If a boundary applies to the lower specification limit for some variables or groups, but not others, enter a value of 0 or 1 for each group or variable in the analysis. 1 indicates that the lower spec is a boundary for that variable or group, and 0 indicates that the lower spec is not a boundary for that variable or group.
You can enter one value, multiple values, or a column of values. If you enter one value, it applies to all variables or groups. If you enter multiple values or a column of values, the values correspond sequentially to the columns that you entered in Variables or to the groups in the By variables column.
For example, suppose you enter C1 C2 in Variables, and 3 5 in Lower spec. If 3 is a boundary for C1, but 5 is not a boundary for C2, select Boundary and enter 1 0. The 1 is for C1, and the 0 is for C2.
Select to define an upper specification limit as a boundary only if it is not possible for measurements to fall above the Upper spec value. If a boundary applies to the upper specification limit for some variables or groups, but not others, enter a value of 0 or 1 for each group or variable in the analysis. 1 indicates that the upper spec is a boundary for that variable or group, and 0 indicates that the upper spec is not a boundary for that variable or group.
You can enter one value, multiple values, or a column of values. If you enter one value, it applies to all variables or groups. If you enter multiple values or a column of values, the values correspond sequentially to the columns that you entered in Variables or to the groups in the By variables column.
For example, suppose you enter C1 C2 in Variables, and 10 8 in Upper spec. If 10 is a boundary for C1, but 8 is not a boundary for C2, select Boundary and enter 1 0. The 1 is for C1, and the 0 is for C2.
When you define a specification limit as a boundary, Minitab reports the expected capability indices related to that specification limit as missing values (*). Therefore, define a limit as a boundary only if it is impossible for measurements to fall beyond the limit. For example, an upper specification limit of 100% purity is a boundary because exceeding 100% purity is impossible. A lower specification limit of 0% purity is a boundary because falling below 0% purity is impossible.