This chart is a graphical representation of the Gage R&R section of the Session window output.

The sources of variation that are represented in the graph are:

·    Total Gage R&R, which is the variation due to the measuring system including multiple operators using the same gage.

·    Repeatability, which is the variability in measurements obtained when the same part is measured multiple times by the same operator.

·    Reproducibility, which is the variability in measurements obtained when the same part is measured by different operators at the various conditions defined by the factors in the model..

·    Part-to-Part, which is the variability in measurements across different parts.

Separate bars represent:

·    %Contribution, which is 100 times the variance component for that source divided by the total variance.

·    %Study Variation, which is 100 times the study variation for that source divided by the total study variation.

·    %Tolerance (if a process tolerance or a specification limit is given in the Options subdialog), which is 100 times the study variation for that source divided by the process tolerance.

·    %Process (if a historical standard deviation is given in the Options subdialog), which is 100 times the study variation for that source divided by the process variation.

In a good measurement system, the largest component of variation is Part-to-Part variation. If instead you have large amounts of variation attributed to Gage R&R (Repeatability and/or Reproducibility), corrective action is needed.

For the refraction data, you can see that measurement system accounts for about the same amount of variation as the part-to-part variation. Specifically, most of the variability can be accounted for by the inaccuracy of the measurement system (Repeatability).