Tests
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Stat > Quality Tools > Capability Sixpack > Normal > Tests

Lets you select a subset of the 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.

You can set preferences for the tests to perform and for the sensitivity of these tests using Tools > Options > Control Charts and Quality Tools > Tests.

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.

Subgroup sizes must be equal to perform the tests.

Dialog box items

Tests For Special Causes (default definitions)

Perform all eight tests: Choose to perform all eight tests for special causes.

Choose specific tests to perform: Choose to specify a subset of the eight tests, then check any combination of the tests listed below.

One point more than 3 standard deviation from center line

Nine points in a row on same side of center line

Six points in a row, all increasing or all decreasing

Fourteen points in a row, alternating up and down

Two out of three points more than 2 standard deviation from center line (same side)

Four out of five points more than 1 standard deviation from center line (same side)

Fifteen points in a row within 1 standard deviation of center line (either side)

Eight points in a row more than 1 standard deviation from center line (either side)