This expanded and revised edition presents a pragmatic account of how to design, test, and/or select instruments, methods and procedures for measuring variables in clinical, educational and research settings. It provides the reader with knowledge and skills to address the increased number of complex issues threatening the reliability and validity of measurement efforts and presents expansive reference sources. New features of this title include: added content on the use of Rasch Modeling and Structural Equation Modeling; addition of a Part III, reflecting the increased importance of and focus on use of the internet in the conduct of research and measurement efforts; more emphasis on computer based testing; and, new chapters that focus on clinical data collection methods, including clinimetrics, and the unique challenges of conducting research in clinical settings and situations where strict experimental control and standardization are not optimal.