Rating scales, scales of measurement, issues of reliability: resolving some critical issues for clinicians and researchers.

We focus upon several broad issues that are of concern to clinicians and clinical researchers in the areas of biobehavioral and biomedical research, including, but not limited to, the fields of psychiatry, psychology, neuropsychology, and neurology. These issues are the critical reassessment of S. S. Stevens' quadripartite conceptualization of scales of measurement; the application of criteria to determine the clinical significance of reliability estimates; the detection of subsets of reliable and unreliable raters, when the overall level is of little clinical import; and finally, the application of Kappa statistics when multiple raters evaluate a single case.