To create an Attribute Chart

To create an Attribute Chart
Note: In order to create an Attributes control chart, you must first have an Attributes 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.

Attribute(s): From the drop-down list, select the column name(s) 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. You may select more than one column in the list, in which case the counts for each characteristic will be numerically combined. To select a continuous range of column names, click on the first entry you want, and either hold down the left mouse button as you drag across the others, or press the shift key as you click on the last entry you want included. You may choose a discontinuous range by holding down the CTRL key as you click on entries with the left mouse button.

Analysis/Chart Format Options from: Choose a single column from the drop down list from which to obtain the Analysis Options and Chart Format Options used for the chart.

Statistics: Select this option for showing the Chart Window as a split window, with two panes separated by a moveable sash.

Sample Size selection

If you have set this selection in the Analysis Options for the column selected above, then this selection will be shown.

Constant (p, u, Np or c charts) Choose this if the counts in the column you are analyzing relate to a fixed sample size. Enter the sample size in the text box here.

From Col (p or u charts) Choose this if the counts in the column you are analyzing relate to a varying sample size. The sample sizes should be in the column that you select from the drop down list box. When you perform an analysis then, for each row of the data, the program will use the corresponding sample size in the selected column. The control limits will vary with the sample size; because of better certainty with larger samples, the control limits are tighter.

Base limits on mean sample size: Check this to use the average sample size to determine control limits. In this case, control limits will be constant for the region.

Note: This is only recommended if the subgroup size does not vary by more than about 20%. If there is excessive variation in subgroup size, control chart sensitivity will be lost.

Proportions entered (p, u, np or c charts) In this case, enter the sample size in the text box, which are needed to calculate the control limits. The sample size must be constant for all groups.

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 appropriate Attribute Chart window.