Psychometric considerations in evaluating health-related quality of life measures

How does one determine if a measure of health-related quality of life (HRQL) is adequate for clinical trials? Psychometric methods are frequently used to answer this question. What is psychometrics all about? In this paper we address these questions, discussing common psychometric evaluation procedures applied to HRQL measures. Specifically, we discuss issues regarding the evaluation of reliability and validity (including responsiveness).