In their article Ruscio et al. (Ruscio, Seaman, D'Oriano, Stremlo, & Mahalchik, this issue) present a comparative study of some of the different variants of the "h" index. The study evaluates a total of 22 metrics, including the "h" index and "h"-type indices, as well as other conventional measures. The novelty of their work is to a large extent…

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…

Background/Context: Two key uses of international assessments of achievement have been (a) comparing country performances for identifying the countries with the best education systems and (2) generating insights about effective policy and practice strategies that are associated with higher learning outcomes. Do country rankings really reflect the…

This paper is meant to highlight the occurrence of Simpson's Paradox when using aggregated data obtained from two IEA studies in Israel, while ignoring the effect of a powerful intervening variable in the local context--the ethnicity factor. It will demonstrate faulty conclusions regarding either the absence of relationships between a contextual…

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…

A cross-case analysis of four National Science Foundation (NSF) case studies identified both unique details and common themes related to promoting the use and influence of multisite evaluations. The analysis provided evidence of diverse evaluation use by stakeholders and suggested that people taking part in the multisite evaluations perceived…

Why do we continue to see evidence that nonprofit staff feel like outcome measurement is missing important aspects of their work? Based on an analysis of over 1,000 pages of material in 10 outcome measurement guides and a focused literature review of frontline work in three types of nonprofit organizations, this article shows that existing outcome…

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…

Child assessment practices in English and Korean preschools were compared by analysing data from interviews with educators, examples of child assessment, and official documents from each country. Child assessment in England was systematically implemented and characterised by several methodological and procedural strengths, whereas assessment in…

This brief considers the problem of using value-added scores to compare teachers who work in different schools. The author focuses on whether such comparisons can be regarded as fair, or, in statistical language, "unbiased." An unbiased measure does not systematically favor teachers because of the backgrounds of the students they are…

Cognitive ability tests are widely used in organizations around the world because they have high predictive validity in selection contexts. Although these tests typically measure several subdomains, testing is usually carried out for a single subdomain at a time. This can be ineffective when the subdomains assessed are highly correlated. This…

In the last four years McKinsey and Company have produced two highly influential reports on how to improve school systems. The first McKinsey report "How the world's best-performing school systems come out on top" has since its publication in 2007 been used to justify change in educational policy and practice in England and many other…