In the analysis of variance method, the variance can be decomposed into four categories: Parts, Appraisers, the Interaction between parts and appraisers, and the Repeatability of the gauge (AIAG, 2010). Note that randomization is an important factor to the success of the ANOVA method – See section 3.2.6. 4.2 Average Range Method The Average Range methodology will calculate the percent of process variation of the overall measurement system, including its main components; repeatability, reproducibility and part variation.