This document discusses measurement system analysis (MSA) and gauge repeatability and reproducibility (R&R) studies. MSA is used to evaluate different aspects of a measurement system like bias, linearity, stability, repeatability and reproducibility. R&R studies focus specifically on repeatability and reproducibility. Key terms are defined, including bias, repeatability, reproducibility, stability, linearity, attribute R&R parameters like effectiveness, misses, false alarms, and bias, and how to analyze variable measurement data using analysis of variance. Guidelines for acceptable levels of R&R parameters are also provided.