Revision Proposal of the Number of Distinct Categories Definition and Acceptance Criteria for Measurement System Validation
6 Pages Posted: 23 Sep 2022
Date Written: September 11, 2022
Abstract
%GRR and Number of Distinct Categories (NDC) are widely used as measurement system capability indicators. However, the usually accepted calculation formula of the NDC is assigned a coefficient whose origin have led to the coexistence of two different and misleading interpretations of the NDC. We recommend to remove this coefficient in order to stick to the measurement system resolution definition or equivalent signal-to-noise concept. We also propose a realignment of the %GRR and NDC acceptance thresholds.
Keywords: quality management, measurement system analysis, gage R&R, measurement system resolution, number of distinct categories
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