Dr. Don Wheeler has another excellent article posted at Quality Digest, explaining how to use I-MR (he calls them XmR) charts to evaluate the precision and bias of a measurement system. You can read his treatise here.
There are several tools for evaluating measurement systems, including Gage R&R and Intraclass Correlation Coefficient. None are quite as simple and elegant as the one Don discusses.
Here is Don, quoting Churchill Eisenhart at Nation Bureau of Standards, back when that is what the organization was called:
Until a measurement process has been “debugged” to the extent that it has attained state of statistical quality control, it cannot be regarded, in any logical sense, as measuring anything at all.