Some relationships between gage R&R criteria

In this paper, several commonly used gage repeatability and reproducibility (R&R) acceptance criteria are discussed. The number of distinct categories (ndc) is equivalent to an acceptance criterion based on another standard metric, the ratio of the estimated measurement system standard deviation to the estimated overall standard deviation of the measurements. This implies that the criterion based on ndc could be considered redundant. Several acceptance criteria are revisited and compared, including a discussion of more objective measures of capability based on misclassification rates. The relationship between ndc and the discrimination ratio is also given.