Developing a Psychometric Ruler: An Alternative Presentation of Rasch Measurement Output

Keywords

Psychometric Ruler, Rasch Measurement Output, Rasch model

Abstract

Rasch measurement is one of the most popular analytical techniques available in the field of psychometrics and is quickly becoming the norm for instrument validation studies. The advantages of Rasch modeling have been well documented in the literature (see Wright and Stone, 1979; Wright and Stone, 1999; Smith, Jr. & Smith, 2004; and Bond & Fox, 2007). Despite the advantages of Rasch measurement, many researchers and consumers of information have acknowledged that there is much room for improvement with regard to output reporting. This is not to say measurement software creators have failed by any means, but being able to interpret Rasch output, such as the “item map” (or Wright Map), can be an arduous task. In the authors quest to more effectively convey the valuable information obtained from Rasch analyses, this work is intended to provide an alternative presentation of Rasch output that is more user-friendly and easily interpreted by consumers of research. Particularly, the authors will produce a psychometric ruler comparable to that of the physical sciences that can be interpreted in the same way. This article will begin by providing an overview of objective measurement in the social and behavioral sciences, followed by a brief synopsis of Rasch measurement. A discussion of the psychometric ruler will be presented, followed by an explanation as to how readers can produce one from their own Rasch output. A demonstration will be provided on a universally interesting topic, namely measuring skepticism. A presentation of the psychometric ruler will follow, accompanied by a discussion of how to interpret the results. Strengths, weaknesses and implications of the psychometric ruler will also be discussed.

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