Gage Agreement Folio: Plots

The following plots are available in gage agreement folios. They allow you to visually display the data and compare the accuracy and precision of the gages.

The Difference vs. Mean plot shows the difference between the gage's measurements of each part versus the mean measurement of the part. (These are the same values in the Difference and Grand Average columns in the Part Summary.) If points seem to follow a trend, then the linearity of the gages may be different. The control limits are marked with red dotted lines near the top and bottom of the chart. If a point is out of control, then the difference (i.e., y-axis value) associated with that point is significantly larger than the differences associated with the other points.
The Average Reading plot is used to investigate whether the two gages have the same accuracy (linearity and bias). If they do, then the average readings from the first vs. second gages should follow the black 45-degree reference line that passes through the origin. The blue line is a regression line fitted to the data points. The closer the fitted line is to the reference line, the more likely it is that the gages have the same accuracy.
The Gage Repeatability plot shows the calculated repeatability variance for each gage, as well as the upper and lower confidence bounds on the repeatability. The confidence level used is determined by the risk level specified on the Analysis Settings page of the Data tab control panel. If the confidence bounds for the two gages overlap, then the gages have the same repeatability.