Evidence for the reliability of measures and validity of measure interpretation: a Rasch measurement perspective.

In an era of high stakes testing and evaluation in education, psychology, and health care, there is need for rigorous methods and standards for obtaining evidence of the reliability of measures and validity of inferences. Messick (1989, 1995), the Standard for Educational and Psychological Testing (American Psychological Association, American Educational Research Association, and National Council on Measurement in Education, 1999), and the Medical Outcomes Trust (1995), among others, have described methods that may be used to gather evidence for reliability and validity, but ignored the potential role Rasch measurement may contribute to this process. This article will outline methods in Rasch measurement that are used to gather evidence for reliability and validity and attempt to articulate how these methods may be linked with the current views of reliability and validity.