The nature of percentile ranks scores is explored using concrete heuristic examples. It is explained why arithmetic operations require measurement on equal-interval scales, and that percentile ranks are not measured on equal-interval scales and therefore may not be added or averaged. The consequences of inappropriately adding percentile ranks are…

A lawsuit involving the National Board for Respiratory Therapy illustrates that certification examinations are vulnerable to complaints of discrimination and employers' misuse of test results. The board's five-step process--position-viability study, personnel survey, job analysis, item writing/test development, and criterion-related validity…

States use many high-stakes assessments to make decisions about individuals. These tests may be criticized by those who believe that their purpose or application is discriminatory. Because litigation is time consuming and costly, it is advantageous for states to plan assessments carefully to maximize legal defensibility. This handbook is designed…