The Average Distance Between Item Values

Abstract

This article presents a method for assessing the internal consistency of scales that works equally well with short and long scales, namely, the average proportional distance. The method provides information on the average distance between item scores for a particular scale. In this article, we sought to demonstrate how this relatively simple statistic could be calculated and present examples that show its advantage over traditional methods. Simulation and empirical tests were conducted to establish standards for the average proportional distance of scores. The implications for test construction are discussed with a particular emphasis on the advantages of developing shorter scales for psychological and educational research.