To create a Process Capability Chart

To create a Process Capability Chart
Note: In order to create any of the Variables control charts, you must first have a Variables data file open, containing the data you wish to analyze.

The Chart Options dialog box. is available by choosing New Chart from the Chart menu when a Data Editor is the current window, or Amend Chart from the Chart menu when a Chart Window is the current window. The Chart Options dialog box is a dynamic dialog box, since the options available on the right side of the dialog box will change depending on your selection on the left side of the dialog box. Therefore, you must first select the type of chart you wish to create.

Variable: From the drop-down list, select the column name containing the data you want analyzed on the chart. The program pre-selects the single column that was active (cursor location) in the data editor.

Subgroup Size: Click on the up/down buttons, or enter via the keyboard, any number between two and thirty two thousand. The program pre-selects the subgroup size designated in the Column Format dialog box for the selected variable.

Note: The subgroup size influences the analysis by its affect on Process Sigma, which is used in calculating the Capability Indices.

· If subgroup size = 1: the Individual-X's Moving Range chart is used to calculate process sigma.
· If subgroup size > 1: the X-bar's Sigma chart is used to calculate process sigma.

You may also choose a range of data to be used in the analysis. The default selection uses all the data in the selected column(s). You may also select a range of data, by selecting the subgroups to be analyzed.

Click on OK to advance to the Individual-X Chart window.