Data considerations for Attribute Gage Study (Analytic Method)

To ensure that your results are valid, you must adhere to the following data requirements.

AIAG Method (default)

Each study part must have a known measurement
A reference value is the known standard measurement of a part. You use the reference value as a master value for comparison during measurement systems analysis. For example, you use a part that has a known weight of 0.025 g to calibrate your scales.
Select 8 parts that span the tolerance limit of interest
To investigate the bias of the gage, select 8 parts for your study that span the tolerance limit of interest and are at approximately equidistant intervals.
The smallest number of acceptances must equal 0, and the largest number of acceptances must equal 20
If you specify the lower tolerance limit, the smallest part must have 0 acceptances, and the largest part must have 20 acceptances.
If you specify the upper tolerance limit, the smallest part must have 20 acceptances, and the largest part must have 0 acceptances.
The remaining 6 parts must have greater than 0, but less than 20 acceptances.
Note

For the full analysis, including the bias calculation, you must have exactly 8 parts —1 with the smallest accept number, 1 with the largest accept number, and 6 with acceptances between 1 and 19.

  • If you have less than 6 parts with acceptances between 1 and 19, the analysis does not run.
  • If you have more than 6 parts with acceptances between 1 and 19, Minitab does not evaluate bias.
  • If you have more than 8 parts, but you have exactly 6 parts with acceptances between 1 and 19 and additional parts with acceptances of 0 and 20, Minitab ignores the additional parts at 0 and 20 and runs the analysis.

Each part must be measured by the gage multiple times
With the AIAG method, you must have exactly 20 trials per part for a full analysis. Minitab performs a partial analysis if you have at least 15 trials; however, Minitab will not provide the bias calculations unless you have 20 trials per part.

Regression Method

Each reference part must have a known measurement
A reference value is the known standard measurement of the reference part. You use the reference value as a master value for comparison during measurement systems analysis. For example, you use a reference part that has a known weight of 0.025 g to calibrate your scales.
Select at least 8 parts that span the tolerance limit of interest
To investigate the bias of the gage, select at least 8 reference parts that span the tolerance limit of interest and are at approximately equidistant intervals.
Each part must be measured by the gage multiple times
With the regression method, you must have at least 15 trials per part.
The smallest number of acceptances must equal 0, and the largest number of acceptances must equal the number of measurements for the part
If you specify the lower tolerance limit, the smallest part must have 0 acceptances, and the largest part must have the maximum number of possible acceptances (at least 15 with the regression method).
If you specify the upper tolerance limit, the smallest part must have the maximum number of possible acceptances (at least 15 with the regression method), and the largest part must have 0 acceptances.
You must have at least 6 parts between 1 acceptance and the maximum number of acceptances.
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