The analysis produces the Analysis Of Mean Ranges (ANOMR) chart when operators measure each part 8 times or less. The chart has a reference line at the average range across all parts measured by each operator. The chart includes decision limits that test for differences in test-retest error among operators. The decision limits use the following formulas:
- Upper Decision Limit (UDL)
- UMR ×
- Lower Decision Limit (LDL)
- LMR ×
The values of UMR and LMR are from the table of values in Wheeler (2006)1. The value of 
is the average of all the ranges.
1 Wheeler,
Donald (2006). EMP III: Evaluating The Measurement Process & Using
Imperfect Data. SPC Press
