Components of Variance of Scales With a Bifactor Subscale Structure From Two Calculations of α

Since Cronbach's (1951) elaboration of α from its introduction by Guttman (1945), this coefficient has become ubiquitous in characterizing assessment instruments in education, psychology, and other social sciences. Also ubiquitous are caveats on the calculation and interpretation of this coefficient. This article summarizes a recent contribution (Andrich, 2015) on the use of coefficient α which complements these many caveats. It shows that in the presence of a simple bifactor structure of a scale where unique components of variance are homogeneous in magnitude, three components of variance and the common latent common correlation among the subscales can be calculated from the ratio of two calculations of α, one at the level of the items, the other at the level of the subscales. It was suggested that these two ready calculations and their interpretation, and the reporting of all four indices in the analysis of scales with a subscale structure, would reduce the misinterpretation of this coefficient. An illustrative example of the application of the calculations is also shown.     

Using Consumer Data to Illustrate How the Library Channel Drives Digital Sales

The library channel is often underappreciated as a key part of a publisher’s business strategy. In an age where publishers are constantly seeking new revenue and marketing opportunities, presence in the library—digitally—can yield significant growth. This paper examines the library channel, its business model based on library lending, the performance of eBooks and audiobooks across all subjects, and consumer reading behavior. Digital Book Clubs, a relatively new phenomenon, are also defined and illustrated with examples demonstrating the library’s valuable role in increasing discoverability and ultimately sales.     

The effect of context on students’ reasoning about forces

When attempting to solve closely related problems in science, students will often respond to irrelevant contextual features in the questions rather than generalizing their conceptions over the range of relevant situations. In this study, a group of 40 students (one group of 15‐16‐year‐olds and another of preservice science teachers) was surveyed and interviewed to determine the effect of context on the reasoning which they used to solve problems concerning the forces acting on objects in linear motion. It was found that the younger group of students were influenced by contextual features such as the speed, weight and position of the moving object, the direction of the motion and their own personal experience of the context. There were clearly two types of contextual effects ‐‐ primary and secondary, which are described. The older group of students was generally less affected by context and thus more consistent in their reasoning.     

Innovation in Education ‐‐ the Case for the Interactive Videodisc in Schools

Abstract

This article explores the case of the videodisc in the context of the progress of technological innovation in the field of education. It looks at what the medium has to offer and the ways in which it is currently being used, before going on to consider the factors that may impede its acceptance and what can be done towards ensuring its implementation.     

Developing narrative skills through case-studies

This article describes the adaptation of ‘story grammar’ to developing the subject understanding and literacy of 14–16-year-old students. ‘Story grammar” analyses the structure of episodes of a typical story and it was developed through research into the narrative development of younger, frequently language-delayed, children. Reasons for expecting this story grammar to provide a helpful basis for teaching older students are summarized. An application of story grammar in teaching business studies is described through the activities designed for students and evidence from students' work. Implications for understanding of literacy in a subject context are discussed.