Complete the following steps to interpret a nested gage R&R study. Key output includes variability estimates, and graphs of the measurements and measurement variability.

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

- Operator: The variation that is from the operators.
- Part (Operator): The variation that is from the parts that are nested within each operator.
- Error or repeatability: The variation that is not explained by part or operator.

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

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

If an operator can measure a part only once (such as with destructive testing), you must be able to assume that all parts within a single batch are identical enough to claim that they are the same part. If you are unable to make that assumption then part-to-part variation within a batch will mask the measurement system variation.

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 (operator) graph
- Shows whether multiple measurements for each part by each operator are close together, which indicates between-part variability and within-part variability.
- Measurements by operator graph
- Shows whether differences between operators are small compared to the differences between parts.