Gauge R&R (One Equipment, multiple part, multiple Appraisers)

The BIS.Net Team BIS.Net Team

A Gauge R&R (GRR), is used to study repeatability (by the same operator) and reproducibility (by different operators). For this application, consisting of multiple parts an Analysis of Variance is required to extract as much information as possible. Notably the ANOVA method, as opposed to the historical control chart methods, can detect interaction effects between appraisers and parts (items) measured.

Each appraiser must test the same part at least twice. At least two parts must be measured, and all appraisers must test the same number of parts the same number of times. Each part has a different Reference value.

A common mistake is to enter the actual measurements into the analysis. That serves little purpose because the analysis will only conclude that there is significant part variation, which is already known. The objective is to establish if bias varies with the different parts. Hence the difference between the actual value minus the reference value must be entered.

An example of input is shown below.

Appraisers in this instance are coded as A, B, C. Parts are coded as 1,2,3.

Output includes an Analysis of Variance, Reproducibility Chart, Dart Board, A Probability Plot and an Interaction Chart