Specify the display options for Xbar-R Chart (Display tab)

On the Display tab of the Xbar-R Chart dialog box, specify the tests for special causes and the sigma limits to display.

Tests for special causes

Minitab provides eight tests for special causes. By default, Minitab uses only Test 1. Select additional tests based on company or industry standards. Use the tests to determine which observations to investigate, and to identify the specific patterns and trends in your data.

Specify whether to perform only test 1, all, or no tests for special causes.

Perform only test 1 (1 point > 3 standard deviations form the center line)
Select to perform Test 1, which identifies subgroups that are unusual compared to other subgroups. Test 1 is universally recognized as necessary for detecting out-of-control situations.
Perform all tests for special causes
Select to perform all four tests for special causes.
Perform no tests
Select to perform none of the tests for special causes.

Display additional sigma limits above and below the center line

You can display ±1 and/or ±2 additional standard deviation lines on your control chart. Values that you enter affect only the line position on the control chart, not the test results.

Default 3 sigma limits
Additional sigma limits at 1 and 2 standard deviations
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