It will be no surprise to learn that Walker Runn has bumbled himself into a corner. Bias in a measurement system is the difference between the actual measurements taken, and the true value (often called "reference") of what is being measured.
As impressive as this equation seems, all it does is test whether there is significant difference between the actual measurement taken by the measuring system, and the actual size of the part being measured. Another way of seeing this: it indicates the amount that you've missed by.
An easier way to determine this is to simply click a few keys on GAGEpack and then show the printout to the auditor. In this case, I used data from page 87 of the MSA book, with a bias of .0067. GAGEpack shows this in scientific notation 6.66666 E - .03.