Psychometrics has recently undergone extensive criticism within the medical education literature. The use of quantitative measurement using psychometric instruments such as response scales is thought to emphasize a narrow range of relevant learner skills and competencies. Recent reviews and commentaries suggest that a paradigm shift might be…

This commentary examines the role of the unit from the perspective of the definition of measurement in physics as the ratio of two magnitudes, one of which is defined as the unit; it is an important and timely contribution to measurement in the social sciences. There are many different points that could be commented upon, but the author will…

Compared to traditional test theory, where person measures are typically referenced to the distribution of a population, item response theory allows for a much more meaningful interpretation of measures as they can be directly compared to item locations. However, Stephen Humphry shows that the crucial role of the unit of measurement has been…

Humphry (this issue) deserves credit for drawing attention to the long-neglected fact that differences in item discrimination parameters are often due to empirical factors and not the product of random error components. In doing so, Humphry offers a psychometrically elegant, coherent, and practically important new model that is more flexible while…

Humphry (this issue) has written a thought-provoking piece on the interpretation of item discrimination parameters as scale units in item response theory. One of the key features of his work is the description of an item response theory (IRT) model that he calls the logistic measurement function that combines aspects of two traditions in IRT that…

Behavioral scientists have struggled with units of measurement for as long as they have struggled with measurement itself. Psychology's sole attempt at an explicit unit of measurement--the Lexile Framework for Reading (Stenner, Burdick, Sanford, & Burdick, 2006)--has been and continues to be ignored by the psychometric "cognoscenti."…

The purpose of this article is to examine the role of the unit in physics in order to clarify the role of the unit in psychometrics. Based on this examination, metrological conventions are used to formulate the relationship between discrimination and the unit of a scale in item response theory. Seminal literature in two lines of item response…

This article presents Stephen Humphry's response to the commentaries for his article "The Role of the Unit in Physics and Psychometrics." The commentaries covered a range of important considerations and implications. Given that the author fully agrees with the majority of the content, attention will be confined mainly to points that call…

Standardizing aspects of assessments has long been recognized as a tactic to help make evaluations of examinees fair. It reduces variation in irrelevant aspects of testing procedures that could advantage some examinees and disadvantage others. However, recent attention to making assessment accessible to a more diverse population of students…

Compared to unidimensional item response models (IRMs), cognitive diagnostic models (CDMs) based on latent classes represent examinees' knowledge and item requirements using discrete structures. This study systematically examines the viability of retrofitting CDMs to IRM-based data with a linear attribute structure. The study utilizes a procedure…

The assessment procedures within Response to Intervention (RTI) models have begun to supplant the use of traditional, discrepancy-based frameworks for identifying students with specific learning disabilities (SLD). Many RTI proponents applaud this shift because of perceived shortcomings in utilizing discrepancy as an indicator of SLD. However,…

Although the Angoff procedure is among the most widely used standard setting procedures for tests comprising multiple-choice items, research has shown that subject matter experts have considerable difficulty accurately making the required judgments in the absence of examinee performance data. Some authors have viewed the need to provide…

In this article, we introduce a person-fit statistic called the hierarchy consistency index (HCI) to help detect misfitting item response vectors for tests developed and analyzed based on a cognitive model. The HCI ranges from -1.0 to 1.0, with values close to -1.0 indicating that students respond unexpectedly or differently from the responses…

This paper describes the process of designing and administering a sufficiently valid and reliable assessment instrument to measure the progress in attainment of adult learners studying numeracy, and discusses some of the inherent difficulties that were involved. The fieldwork took place during 2003-2005 and involved a sample of 34 teachers and 412…

This article reviews issues involved with using norm-referenced measures within an intervention validity model. Methodological examination of intervention validity has become more important as intervention methodologies have become part of federal legislation. However, current practice and federal guidelines often implicitly portray a dichotomy…