Examine the results of a crossed gage R&R study to look for significant sources of
variability in your measurement system. Use the variance components and the graphs of
measurement variability to evaluate repeatability and reproducibility.

Use the ANOVA table to identify which sources of variability are significant. The ANOVA table includes the following terms in the Source column:

- Part: The variation that is from the parts.
- Operator: The variation that is from the operators.
- Operator*Part: The variation that is from the operator and part interaction. An interaction exists when an operator measures different parts differently.
- Error or repeatability: The variation that is not explained by part, operator, or the operator and part interaction.

If you select the Xbar and R option for Method of Analysis, Minitab does not display the ANOVA table.

If the p-value for the operator and part interaction is 0.05 or higher, Minitab removes the interaction because it is not significant and generates a second ANOVA table without the interaction.

Use the variance components (VarComp) and %Contribution to assess the variation for each source of measurement error. The sources are as follows:

- Total Gage R&R: The sum of the repeatability and the reproducibility variance components.
- Repeatability: The variability in measurements when the same operator measures the same part multiple times.
- Reproducibility: The variability in measurements when different operators measure the same part.
- Part-to-Part: The variability in measurements due to different parts.

Ideally, very little of the variability should be due to repeatability and reproducibility. Differences between parts (Part-to-Part) should account for most of the variability.

The gage R&R graphs provide information about the measurement system.

- Components of variation graph
- Shows whether the largest of component of variation is part-to-part variation.
- R chart by operator
- Shows whether any points fall above the upper control limit.
- Xbar chart by operator
- Shows whether most points fall beyond the control limits.
- Measurements by part graph
- Shows whether multiple measurements for each part are close together.
- Measurements by operator graph
- Shows whether differences between operators are small compared to the differences between parts.
- The operator*part interaction graph
- Shows whether the lines that connect the measurements from each operator are similar or whether the lines cross each other.