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Learn the terms, definitions, and techniques for evaluating measurement systems. Understand the concepts of repeatability, reproducibility, accuracy, bias, linearity, and stability. Enhance your understanding of precision and control charts.
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The Certified Quality Engineer Handbook 3rd ed. Ch. 26: Measurement System Analysis Dr. Joan Burtner Certified Quality Engineer Associate Professor of Industrial Engineering and Industrial Management
Ch. 26: Measurement System Analysis Terms and Definitions Gage Repeatability and Reproducibility Variables vs. Attributes Gage R&R Methods Tabular Analysis of Variance Control Charts 2 ISE 428 ETM 591 JMB CH 26 Lecture 1
Terms and Definitions – 1 (Glossary page 630) Gage Repeatability and Reproducibility (GR&R) – measures the capability of a gage to determine if it is suitable for use in its intended application. Repeatability represents the gage variability when it is used to measure the same unit with the same setup or operator. Reproducibility refers to the variability arising from different setups or operators. 3 ISE 428 ETM 591 JMB CH 26 Lecture 1
Terms and Definitions – 2 (Glossary page 638) Repeatability – how close the measurements of an instrument are to each other if such measurements are repeated on a part under the same measuring conditions. (Glossary) Reproducibility – a measure of the degree of agreement between two single test results made on the same object in two different, randomly selected measuring locations or laboratories. (Glossary) 4 ISE 428 ETM 591 JMB CH 26 Lecture 1
Terms and Definitions - 3 Accuracy – the difference between the measurement taken and the actual value of the variable Accuracy – a qualitative term that describes the closeness of alignment between an observed value and an accepted reference value Bias – a quantitative term representing the systematic difference between measurements obtained and the true quantity of interest 5 ISE 428 ETM 591 JMB CH 26 Lecture 1
Terms and Definitions - 4 AIAG – Automotive Industry Action Group Linearity – measures how changes in the size of the part being measured will affect measurement system bias over the expected process range Example: Does bias change significantly as part size increases? Stability – a measure of how the measurement system performs over time. Precision – the variation encountered when the same part is measured repeatedly using the same measurement system (under the same conditions) page 258 6 ISE 428 ETM 591 JMB CH 26 Lecture 1