i MEASUREMENT SYSTEMS ANALYSIS Reference Manual Fourth Edition First Edition, October 1990 Second Edition, February 1995; Second Printing, June 1998 Third Edition, March 2002; Second Printing, May 2003; Fourth Edition, June 2010 Copyright 1990, 1995, 2002, 2010 Chrysler Group LLC, Ford Motor Company, General Motors Corporation ISBN#: 978-1-60-534211-5 ii iii FOREWORD This Reference Manual was developed by a Measurement Systems Analysis (MSA) Work Group, sanctioned by the Chrysler Group LLC, Ford Motor Company, and General Motors Corporation Supplier Quality Requirements Task Force, and under the auspices of the Automotive Industry Action Group (AIAG). The Work Group responsible for this Fourth Edition were Michael Down (General Motors Corporation), Frederick Czubak (Chrysler Group LLC), Gregory Gruska (Omnex), Steve Stahley (Cummins, Inc.) and David Benham. The manual is an introduction to measurement system analysis. It is not intended to limit evolution of analysis methods suited to particular processes or commodities. While these guidelines are intended to cover normally occurring measurement system situations, there will be questions that arise. These questions should be directed to your authorized customer representative. This Manual is copyrighted by Chrysler Group LLC, Ford Motor Company, and General Motors Corporation, with all rights reserved, 2010. Additional manuals can be ordered from AIAG at UaiagT. Permission to reproduce portions of this manual for use within supplier organizations may be obtained from AIAG at UaiagT June 2010 iv MSA 4th Edition Quick Guide Type of Measurement System MSA Methods Chapter Basic Variable Range, Average & Range, ANOVA, Bias, Linearity, Control Charts III Basic Attribute Signal Detection, Hypothesis Test Analyses III Non-Replicable (e.g., Destructive Tests) Alternate Approaches IV Complex Variable Range, Average & Range, ANOVA, Bias Linearity Control Charts III, IV Multiple Systems, Gages or Test Stands Control Charts ANOVA Regression Analysis III, IV Miscellaneous Alternate Approaches IV Other White Papers – available at AIAG website (aiag) NOTE: Regarding the use of the GRR standard deviation Historically, by convention, a 99% spread has been used to represent the “full” spread of measurement error, represented by a 5.15 multiplying factor (where GRR is multiplied by 5.15 to represent a total spread of 99%). A 99.73% spread is represented by a multiplier of 6.0, which is 3and represents the full spread of a “normal” curve. If the reader chooses to increase the coverage level, or spread, of the total measurement variation to 99.73%, use 6.0 as a multiplier in place of 5.15 in the calculations. Note: The approach used in the 4th Edition is to compare standard deviations. This is equivalent to using the multiplier of 6 in the historical approach. Awareness of which multiplying factor is used is crucial to the integrity of the equations and resultant calculations. This is especially important if a comparison is to be made between measurement system variability and the tolerance. Consequently, if an approach other than that described in this manual is used, a statement of such must be stated clearly in any results or summaries (particularly those provided to the customer).