Introduction

Tests and other forms of assessment are designed to provide information that will be useful for some purpose. The degree to which the information provided by a test score is useful, appropriate, and accurate is described by the psychometric concept validity. Validity is the extent to which the inferences (interpretations) derived from test scores are justifiable from both scientific and equity perspectives. For decisions based on test scores to be valid, the use of a test for a particular purpose must be supported by theory and empirical evidence, and biases in the measurement process must be ruled out.

Validity is not an intrinsic property of a test. As many psychometricians have pointed out (e.g. Cronbach, 1971; Messick, 1989; Shepard, 1993), in judging the worth of a ...