PERFORM Help — Variables Chart Setup Form

The following form is used to configure Variables Control Charts. You can select the Location chart type (X, Mean, Median, or None) and the Dispersion chart type (Range, Moving Range, Standard Deviation, Variance, or None). The method to used to calculate control limits, the centerlines, axis labels, and the number of standard errors to use may be selected. Chart calculations can be divided by sets.

There are various configurations available for the file layout. Subgroups can be in rows, in columns indexed by a sample variable, in columns indexed by a specific point count, or individual values in single columns. In addition, data for several charts can be included in a single file. Charts can be distinguished by being in separate columns or by grouping variables.

The recommended selection order is to select the Location Chart type, then the Dispersion Chart type, and then the Dispersion Limit Calculations. This is because selecting the Dispersion Chart type and Dispersion Limit Calculations automatically change the Location calculations to match. The Location Limits can the be changed if desired.

VARSETUP

Speed Buttons

These buttons provide quick access to the following tasks.

Returns to the Main Form.
Opens a Data File.
Displays the Data Editor.
Copies Selection to the clipboard.
Pastes text from the clipboard
Enlarges/Reduces Form size for easier viewing.
Brings up the Main Form.
Brings up the Help file.
Hides the form.

Data Variables

The data variables found in the data editor will be displayed here.

Variable Selection Buttons

These buttons are used to select or deselect the data variables for the subgroups or charts, depending on the layout selection.

Chart Variables

The selected chart variables will be shown here. These variables my represent either separate charts or subgroups found in rows, depending on the layout selection.

Chart Groups

The variables used to generate separate charts will be shown here.

Sample Variable

The data variable defining the sample number is displayed here when this option is selected.

Constant Sample Size Check Box

When this check box is checked, a constant sample size may be entered. Data can then be in a single column and subroups will be generated sequentially by the count entered here.

Set Variable

This variable is used to separate the analysis by sets. When a variable is selected, a vertical bar will be found between each set on the control chart. Separate control limit and centerline calculations will be generated for each set.

Sets do not need to be contiguous. In other words, values with Set=1 can be followed by values with Set=2, which can be followed by values with Set=1. All values with Set=1 will then be used to generate the limits and centerlines for all values of Set=1. This will allow you to separate a middle section.

Layout of Variables

When multiple variables are found in the Chart Variables box, this selection allows you to define whether the multiple variables represent subroups found in rows, or separate variables found in columns.

Location Chart Type

Selection the location chart type here. The options are: X, Mean, Median, or None.

Location Chart Limit Calculations

Select the method to generate the Location Chart Control Limits here.
For X Charts:
Average MR
Median MR
Standard Deviation
Known Standard Deviation
Centerline Only
User Defined
None

For Mean or Median Charts:

Average Range
Median Range
Average Standard Deviation
Median Standard Deviation
Average Variance
Average MR of the Means or Medians
Median MR of the Means or Medians
Standard Deviation of the Means or Medians
Known Standard Deviation
Centerline Only
User Defined
None

Location Centerline

Select the Centerline method here. The option are to use the Mean or Median location statistic, or use a Known Mean.

Positive Limits Only Check Box

When this box is checked, no lower limit will be displayed if it is negative.

Action Button

Click this button to display the Variables Chart.

Dispersion Chart Type

Select the type of Dispersion chart. For X charts you can select the Moving Range or None. For other charts, you can select the Range, Standard Deviation, Variance, or None.

Dispersion Chart Limit Calculations

Select the method to generate the Dispersion Chart Control Limits here.

For MR Charts:
Average MR
Median MR
Standard Deviation
Known Standard Deviation
Centerline Only
User Defined
None

For the Range, Standard Deviation, and Variance Charts:
Average Range
Median Range
Average Standard Deviation
Median Standard Deviation
Average Variance
Average MR of the Dispersion Statistic
Median MR of the Dispersion Statistic
Standard Deviation Dispersion Statistic
Known Standard Deviation
Centerline Only
User Defined
None

Dispersion Chart Centerline

Select the Centerline method here. The option are to use the Mean or Median Dispersion statistic, or use a Known Standard Deviation.

Moving Range Count

Select the number to use to determine the Moving Range. Most typical is to use a range of two successive values. A larger number can be used for processes that change slowly.

Axis Labels

Any variable may be selected to be displayed as X-axis labels. For example, the set number or the count values could be used. This can also be used for a date variable entered as a real number, such as 10.12 for October 12.

Standard Error

The standard error to be used in the control limit calculations may be entered here.

Chart Group Selection Buttons

These buttons are used to select or deselect the data variables used to generate separate charts.

Sample Variable Selection Button

This button is used to select or deselect the data variable to define the sample number.

Set Selection Button

Use this button to select a variable to separate the analysis by sets. When a variable is selected, a vertical bar will be found between each set on the control chart. Separate control limit and centerline calculations will be generated for each set.

PERFORM — Variables Chart Setup Form

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