Gage R&R training is the standard Black Belt level measurement system analysis tool.
R&R stand for repeatability and reproducability; basically making sure measurement systems are valid beyond what can be detected through simple calibration. All calibration finds is bias away from a standard; it's not enough. Never assume your gage is good just because it's calibrated. We've seen companies waste 5-digit figures on incapable gages, and 6-digit figures scrapping good parts because of too much error in their measurement system. Remember, a measurement system includes its user and the process of using the gage. This is often where excessive error resides.