The Accuracy and Consistency of a Series of IRT True Score Equatings

This study investigates a sequence of item response theory (IRT) true score equatings based on various scale transformation approaches and evaluates equating accuracy and consistency over time. The results show that the biases and sample variances for the IRT true score equating (both direct and indirect) are quite small (except for the mean/sigma method). The biases and sample variances for the equating functions based on the characteristic curve methods and concurrent calibrations for adjacent forms are smaller than the biases and variances for the equating functions based on the moment methods. In addition, the IRT true score equating is also compared to the chained equipercentile equating, and we observe that the sample variances for the chained equipercentile equating are much smaller than the variances for the IRT true score equating with an exception at the low scores.     

Moving Toward a Balanced and Effective Response to Internet Music Piracy

Peer-to-peer file sharing of music over the Internet is perceived as a major threat to the international recording industry. This article proposes a novel response to this issue and contrasts this proposed approach with the response of the recording industry to date. The author suggests that piracy could be reduced by changing the distribution of music to an application service provider (ASP) model. Consumers would pay to use software residing on a remote server to play downloaded files but would not possess a complete copy of a physical product that could be reproduced. By selling music as an application, the industry could exercise tighter control over the security of its product without attempting to secure every computer, music player, and CD manufactured. The ASP approach would also limit infringement to the much more serious crime of hacking a corporate server and would eliminate the need to sue large numbers of otherwise law abiding consumers.     

Statistical Models and Inference for the True Equating Transformation in the Context of Local Equating

Based on Lord's criterion of equity of equating, van der Linden (this issue) revisits the so‐called local equating method and offers alternative as well as new thoughts on several topics including the types of transformations, symmetry, reliability, and population invariance appropriate for equating. A remarkable aspect is to define equating as a standard statistical inference problem in which the true equating transformation is the parameter of interest that has to be estimated and assessed as any standard evaluation of an estimator of an unknown parameter in statistics. We believe that putting equating methods in a general statistical model framework would be an interesting and useful next step in the area. van der Linden's conceptual article on equating is certainly an important contribution to this task.     

Learned Helplessness and Psychological Adjustment II: Effects of learning disabilities and low achievement

The present study, a continuation of Valås (2001), is concerned with two categories of low achieving students. The focus is particularly on the consequences of being diagnosed as having learning disabilities compared with not having such a diagnosis. The sample consisted of 1833 students with data collected in grades 4, 7 and 9. Multivariate analyses of variances and analyses of structural equation models showed that students with learning disabilities and low achieving students attributed success in mathematics and first language to ability to a greater extent than other students. They also expressed lower performance expectations in mathematics and verbal skills and showed more helplessness and reported inferior psychological adjustment compared with other students. Moreover, students that were diagnosed as having learning disabilities (LD) and received special education showed more helplessness than the other low achieving children. They also reported lower academic expectations and lower self-esteem. In addition, the results revealed that boys showed more helpless behaviour, as assessed by teachers, than girls. However, on the other hand, girls reported more psychological maladjustment. The conclusion and request is that the process of selection (diagnosing the student as LD) and the organization and implementation of special education should be reconsidered.     

Mapping public support for innovation: A comparison of policy alignment in the UK and France

This paper proposes and tests a three-dimensional model of public support design as a framework to compare public incentives for innovation in firms through time and across countries, and consequently to compare forms of policy alignment of innovation objectives in an economy. Using data on 149 French and British policy programmes from the early 1980s to 2002, this paper shows that policy-makers implement programmes within a different three-dimensional design space in order to align several distinctive objectives and consequently strengthen the impact of governmental measures. Moreover, as the objectives of the national players and policy-makers evolved, the portfolio of innovation policies also evolved in their separate ways. Nevertheless, some similar trends are also observed.     

Phase analysis in maximal sprinting: an investigation of step-to-step technical changes between the initial acceleration,transition and maximal velocity phases

Abstract

The aim of this study was to investigate spatiotemporal and kinematic changes between the initial acceleration, transition and maximum velocity phases of a sprint. Sagittal plane kinematics from five experienced sprinters performing 50-m maximal sprints were collected using six HD-video cameras. Following manual digitising, spatiotemporal and kinematic variables at touchdown and toe-off were calculated. The start and end of the transition phase were identified using the step-to-step changes in centre of mass height and segment angles. Mean step-to-step changes of spatiotemporal and kinematic variables during each phase were calculated. Firstly, the study showed that if sufficient trials are available, step-to-step changes in shank and trunk angles might provide an appropriate measure to detect sprint phases in applied settings. However, given that changes in centre of mass height represent a more holistic measure, this was used to sub-divide the sprints into separate phases. Secondly, during the initial acceleration phase large step-to-step changes in touchdown kinematics were observed compared to the transition phase. At toe-off, step-to-step kinematic changes were consistent across the initial acceleration and transition phases before plateauing during the maximal velocity phase. These results provide coaches and practitioners with valuable insights into key differences between phases in maximal sprinting.