How to Conduct a Gage R&R Study

Jupiterimages/ Images

Gauge R&R otherwise known as ANOVA Gauge R&R is a measurement systems analysis technique that tests a measurement system using Analysis of Variance (ANOVA). The R&R stands for repeatability and reproducibility. In simple terms it tests how accurate a measuring system is. If, for example, you measure a particle, the device or system you use might provide slightly different answers every time you measure the same particle. ANOVA Gauge R&R seeks to remove this variation so different recordings of the same object or target give the same answer.

Decide which specific object or part you want to measure. Use this object as the basis for defining your ANOVA Gage R&R study. The study needs to provide a testable hypothesis or theory. Your study’s theory will concern the natural variation in a particular measurement system and how ANOVA Gage R&R corrects it.

Measure the parts using your established measuring system. Your aim here is to capture as many variations in the measurements as possible. In an ideal situation you will have a number of people able to measure a number of different copies of the same part. Make sure each part is labeled so you can study variations in each object. The larger the survey you can conduct, the more accurate results you can render.

Change one variable at a time. If you had 20 people each measuring one object then rotate the objects between your testers and repeat the tests. Once each tester has tested each object once, rotate the testing machine or device between each of the testers and repeat. In the end each object will have been tested by each tester on each testing device.

Collate and analyze your data. Already you will be able to gauge the variations in the measurements. From the evidence you might be able to determine the root cause of certain variations. For example, if one object is consistently bigger than the others it may be a manufacturing malfunction, if one tester routinely makes errors in measurement it may be their lack of skill and if it is one machine or measuring device making the errors you can identify that as the cause. However, chances are that the variations will be inconsistent.

Download an ANOVA Gage R&R program (see Resources). Choose the program you think best suits your object, objectives and measurement system.

Process your results through the program. It will provide you with a more accurate result for your measurements. Use the adjusted data from the program to demonstrate the effects of ANOVA Gage R&R programs on the natural variation of measurements.



About the Author

Mark Wollacott began writing professionally in 2009. He has freelanced for "Kansai Time Out" and "Kansai Scene" magazines and he has also worked for Travelocity and the Austin Post, writing about travel, business and technology. Wollacott has a Bachelor of Arts in ancient history and archaeology from the University of Wales.

Photo Credits

  • Jupiterimages/ Images