Stat > Control Charts > Xbar, Individuals, Xbar-R, Xbar-S, I-MR-R/S (Between/Within), I-MR > Tests
Stat > Quality Tools > Capability Sixpack (Normal), Capability Sixpack (Between/Within) > Tests
Lets you select a subset of the eight tests for special causes shown in Eight Tests for Special Causes. Each test detects a specific pattern in the data plotted on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
When a point fails a test, Minitab marks it with the test number on the plot. If a point fails more than one test, Minitab marks it by the lowest numbered test, and prints a summary table with complete information in the Session window. See [5] and [25] for guidance on using these tests that detect specific patterns in the data plotted on the chart.You can adjust the sensitivity of the tests with Stat > Control Charts > Define Tests.
Subgroup sizes must be equal to perform the tests.
Stat > Control Charts > Define Tests
You can define the sensitivity of the tests for special causes used with quality control charts. The test definitions stay in effect until you restart Minitab. The range of acceptable values you can enter depends on the test number, as shown below.
Test K can be
(default in parentheses)1 One point more than K sigmas from the center line 1-6 (3)2 K points in a row on same side of center line 7-11 (9)3 K points in a row, all increasing or all decreasing 5-8 (6)4 K points in a row, alternating up and down 12-14 (14)5 K out of K + 1 points in a row more than 2 sigmas from the center line (same side) 2-4 (2)6 K out of K + 1 points in a row more than 1 sigma from the center line (same side) 3-6 (4)7 K points in a row within 1 sigma of the center line (either side) 12-15 (15)8 K points in a row more than 1 sigma from the center line (either side) 6-10 (8)
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