bias linearity in MSA

Because the whole idea of MSA is to understand the sources of variation that exist in your measurement system. If the accuracy of the measuring device varies significantly over the operating range (range of measurement), then don’t you think that is something you’d want to know?

What we are concerned about with gage linearity is that the measurements from a gage should increase linearly with the response or, if a gage is biased, the bias should remain constant over the range of measurements for which that gage is used. While we can tolerate a little non-linearity, it should be small with respect to the normal process variation. As typically defined, the percent linearity of a gage is related to the slope of a regression line fitting bias versus reference value. In general, the smaller the percent linearity the better.