Focus on psychometrics. Aspects of item analysis.

During the course of instrument development, investigators are faced with the challenge of developing a psychometrically sound instrument that has a minimal number of items or components. Although instrument developers may encounter specific problems in relation to different types of tests, there are three areas of concern that are frequently encountered. These concerns relate to (a) instrument length, (b) scale homogeneity, and (c) instrument sensitivity. The purpose of this article is to discuss selected aspects of item analysis in relationship to these three commonly encountered and interrelated areas of concern.