The Define Characteristic dialog box's Property tab contains the following information:
Chart Type : Select one of the available Chart Types for data analysis:
Ind.-X / MR: (Individual-X / Moving Range Chart ) Subgroup Size defaults to 1.
X-Bar / Range: Enter Subgroup Size from 2 to 10 and Subgroup Orientation. Specify Batch Means if applicable.
X-Bar / Sigma: Enter Subgroup Size (2 or larger) and Subgroup Orientation. Specify Batch Means if applicable.
Run Chart: Subgroup Size defaults to 1.
Moving Average / Range Chart: Enter Subgroup Size from 1 to 10 and a Moving Size from 2 to 10.
Moving Average / Sigma Chart: Enter Subgroup Size (2 or larger) and a Moving Size from 2 to 20.
P Chart: Enter Sample Size
U Chart: Enter Sample Size
Np Chart: Enter Sample Size
C Chart: Enter Sample Size
Note: Additional charts for analyzing multiple Characteristics are available in the Analysis branch.
Curve Fit: Choose one of the following options from the drop down list, which is applied to the Individual-X control limits, the curve displayed in the Histogram (if shown), and the Process Capability Indices calculations:
Normal: Uses the Normal distribution to fit a curve to the data.
Johnson: Uses the Johnson Distributions to fit a curve to the data. As an option, you may also enter either the Upper Bound, the Lower Bound, or both to aid in the curve fit. These bounds should be considered the physical limitations of the process. For example, the quality parameter Cycle Time cannot be measured as a negative number, so zero is an appropriate entry for the lower bound when calculating a curve fit for Cycle Time data. Note that the software may not need an entered lower bound to predict process limits within the physical bounds of the process. In this case, the resulting curve fit is identical whether the bound is entered or not entered.
Auto Drop: Select this option to drop out of control subgroups in computing control limits and other process statistics. If this option is selected, out of control subgroups will still be plotted on charts, but will not be used in computing the statistics for the data set.
For X-Bar and Individual-X control charts, the Auto Drop option drops subgroups in the following order:
1. Drops points out of control on the Range (or Sigma) chart from both the Range (or Sigma) and X-bar (or Individual-X) chart
2. Drops points out of control on the X-bar (or Individual-X) chart from only the X-bar (or Individual-X) chart. This allows the Range (or Sigma) chart to us the maximum possible number of subgroups to estimate variation.
High Spec: Enter an optional numeric Upper Specification Limit (upper specification limit, USL) for this process characteristic.
Note: Specification Limits cannot be drawn on X-Bar charts, since the specification limits apply to the observations while the plotted points and control limits apply to the subgroup averages. For other applicable charts, the Show _ Spec on Chart option in the Format tab must be selected for the specification line to be visible on the chart.
Low Spec: Enter an optional numeric Lower Specification Limit (lower specification limit, LSL) for this process characteristic.
Note: High Spec must be greater than Low Spec. See also the Note above.
Target: (Not available for P or U charts) Enter an optional numeric Target (aka Nominal) value for this process characteristic.
Note: The Show Target on Chart option in the Format tab must be selected for the target line to be visible on the chart.
Data Prefix: Enter a prefix value (including decimal, if appropriate) that will automatically be applied to entered values. This feature allows for rapid entry of the values following the prefix. For example, if all data values for the Characteristic will start with 12.2, such as 12.23, 12.26, etc. than you can specify the prefix 12.2 to precede all entries. When entering the data, just type 3, tab to next cell, 6, tab to next cell, etc.
Select one of the following buttons:
OK: to add or edit the Characteristic information and return to the launching point for the dialog.
Note: When adding a new Characteristic to a Process (or Analysis), if the entered Characteristic Name already exists for this Process (or Analysis), then an Error message is provided, and the user is returned to the Define Characteristic dialog box to rename the Characteristic.
Cancel: to return to the launching point for the dialog box without adding or editing the Characteristic.