A Measurement System Analysis (MSA) method which assesses the bias and linearity in your measurement system. A Gage Linearity and Bias Study helps you answer whether your measurement system has bias when compared to a standard and whether it has the same bias across the range of your measurements.
For example, you make several types of screws that have different diameters. Is a bias present in your measurement system? Is this bias constant, independent of the size of screw you are measuring?
For example, you have four screw sizes (0.25",.0.5", 1.0", and 2.0") and twelve measurements of each:
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In all screw sizes, bias is present and significant (p < 0.05 for all the reference sizes). For example, for the 0.25" screw, the average bias is 0.0057583. So on average, the diameter measures higher than the reference value. The bias increases with the screw diameter. Because the bias is not constant across the sizes, as indicated by the positively sloped line in the scatterplot, the measurement system also has linearity problems (p = 0.00).
