Study variation

In gage R&R, the amount of variation caused by the measurement system and by the differences between parts. The variation of the measurement system is divided into two components:

·    Repeatability – the variability from repeated measurements of the same part by the same operator

·    Reproducibility (which can be further divided into operator and operator-by-part components) – the variability when the same part is measured by different operators

Minitab also calculates the percent study variation for each component of variation.

By default, the study variation for each component is six times its standard deviation, but you can change the multiplier. AIAG recommends the use of 6 in gage R&R studies because 6 is the number of standard deviations needed to capture 99.73% of the variation from a source.

Ideally, differences between parts should account for most of the variability; and variability from repeatability and reproducibility should be very small.