Rules for Running a
Gauge Capability Study
The following four rules have been taken directly from Measurement
System Analysis, by the Automotive Industry Action Group. They are
fundamental to performing a clean study. Every effort should be made to
abide by these.
The measurements should be made in a random order to ensure that
any drift or changes that occur due to unknown factors will be spread
randomly throughout the study. The operators should be unaware of
which numbered part is being checked in order to avoid any possible
knowledge bias. However, the person conducting the study should
know which numbered part is being checked and record the data
accordingly, that is Operator A, Part 1, first trial; Operator B, Part 4,
second trial, etc.
In reading the equipment, the readings should be estimated to the
nearest number that can be obtained. If possible, readings should be
made to one-half of the smallest graduation. For instance, if the
smallest graduation is 0.0001, then the estimate for each reading
should be rounded to the nearest 0.00005.
The study should be observed by a person who recognizes the
importance of the caution required in conducting a reliable study.
The measurement procedure should be documented and all operators
trained to the procedure prior to the study.
Each operator should use the same procedure - including all steps - to
obtain the readings.