Not every organization is aware of the importance of understanding and quantifying the variation in measurement systems.
Without a good measurement system, there is no way of knowing what the true output of a process really is!
Based on measurements that are taken during manufacturing, an organization may think that it is producing good parts only to find out that the parts are seriously defective or out-of-tolerance because the measuring device used is inaccurate, out-of-calibration, or not stable. When that happens, you might as well be using a rubber ruler for measuring!
R&R Studies are the most widely used techniques for evaluating the variation in a measurement system and determining if the measurement system is acceptable for use. Once a measurement system is found acceptable, it is equally important to institute a formal system to manage the measurement system to ensure that it continues to be reliable and dependable.
Use of structured GR&R techniques with a comprehensive calibration system for measurement devices is the only way to avoid the rubber ruler syndrome.