A Primer on the One-Parameter Rasch Model.

Abstract

The Rasch measurement model improves on traditional test construction by creating tests in which the person’s ability is independent of the sample of items used and the norm group used to calibrate the test. This article is an introductory review of the Rasch Model and describes properties of the Item Characteristic Curve (ICC) and discusses the utility of having person ability and item difficulty on a common scale.