The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) aims to provide “consistent and reliable acquisition, analysis, communication, and utilization of medical information through a single set of standards. Two physicians, following the methods of the [AMA] Guides to evaluate the same patient, should report similar results and reach similar conclusions.” In addition, the AMA Guides emphasizes that “[c]onsistency tests are designed to ensure reproducibility and greater accuracy.” If findings are inconsistent, the examiner may choose not to base an impairment rating on them, but, as with any biological measurements, some variability and normal fluctuations are inherent in permanent impairment ratings. Specifically, two measurements by the same examiner on two separate occasions or by two trained observers using the AMA Guides are consistent if they fall within 10% of each other. Repeated measurements may decrease error, and examiners should observe for consistencies in both behavior and findings. The musculoskeletal chapters of the AMA Guides provide specific directions in terms of consistency of measurements (eg, the number of measurements that should be taken using each test), allowable variations in measurements taken at different times, reproducibility of results on different occasions or by two or more trained observers, and the validity of these measurements. Inconsistent findings cannot be used to rate impairment.