Developments in WIS Development

This paper presents findings from a longitudinal field study of web-design undertaken in a webdevelopment company. The main contribution is a comparison of some early predictions on the implications of the increased usage of www-technologies for more complex information systems and core findings from two field studies of a specific web-development work setting. The two studies are snapshots from a longitudinal study. Focus in the studies has been on organization of the development work, essential characteristics of the development work, and core characteristics of the products developed. Many of the core problems to be handled in web-based information systems (WIS) development are quite analogous to challenges known from traditional information systems development, although the pace and the number of involved competencies increase, there is a lack of standards in many areas, and there is an increase in communication problems between the different competence groups

Fitting the Mixed Rasch Model to a Reading Comprehension Test: Identifying Reader Types

Standard unidimensional Rasch models assume that persons with the same ability parameters are comparable. That is, the same interpretation applies to persons with identical ability estimates as regards the underlying mental processes triggered by the test. However, research in cognitive psychology shows that persons at the same trait level may employ different strategies to arrive at the solutions. This is a major threat to the construct validity of a test since the construct representation of the test changes for different classes of respondents. In this study a reading comprehension test composed of 20 multiple-choice items is analysed with mixed Rasch model. Findings show that a two-class model fits the data best. After investigating class specific item profiles the implications of the study for test validation along with the contribution of the research to our understanding of reading processes are discussed. Accessed 7,812 times on https://pareonline.net from March 05, 2013 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

The Merger Incipiency Doctrine and the Importance of Redundant Competitors

The enforcers and the courts have not implemented the merger incipiency doctrine in the vigorous manner Congress intended. We believe one important reason for this failure is that, until now, the logic underlying this doctrine has never been explained. The purpose of this article is to demonstrate that markets’ need for “protective redundancy” explains the incipiency policy. We are writing this article in the hope that this will cause the enforcers and courts to implement significantly more stringent merger enforcement.To vastly oversimplify, the current enforcement approach assumes that if N significant competitors are necessary for competition, N-1 competitors could well be anticompetitive, but blocking an N 1 merger would not confer any gains. Because many enforcers and judges erroneously assume that mergers among major competitors usually result in significant gains to efficiency and innovation, they believe that blocking mergers to the N 1 level would impose significant costs on the economy. Why should enforcement preserve apparent “redundancy”? First, the relationship between concentration and competition, and between concentration and innovation, is uncertain. Underestimating the minimum necessary number of firms needed for competition and for innovation is likely to result in harm to consumer welfare. Second, one or more of the N firms frequently can wither or implode as a result of normal competition, or from an unexpected shock to the market, often surprisingly quickly. This leaves only N-1 or N-2 remaining significant competitors. Finally, when enforcers challenge a merger that would have resulted in N competitors, they often allow the merger subject to complex remedies. But if the remedy fails, as they often do, the market will have too few competitors by the enforcers’ own estimate. Taken together these scenarios often leave markets with too few firms. The attenuation of the incipiency doctrine has allowed many mergers that have resulted in higher prices and lower levels of innovation. This has been shown by recent empirical work evaluating the consequences of major mergers. Moreover, other empirical work shows that significant mergers rarely produce significant efficiency gains and often result in losses to innovation.A revitalized incipiency doctrine would retain the “protective redundancy” that would preserve competition, while sacrificing little or nothing in terms of efficiency or innovation. The enforcers and the courts should implement this policy much more aggressively

Evaluation of Item Response Theory Models for Nonignorable Omissions

When competence tests are administered, subjects frequently omit items. These missing responses pose a threat to correctly estimating the proficiency level. Newer model-based approaches aim to take nonignorable missing data processes into account by incorporating a latent missing propensity into the measurement model. Two assumptions are typically made when using these models: (1) The missing propensity is unidimensional and (2) the missing propensity and the ability are bivariate normally distributed. These assumptions may, however, be violated in real data sets and could, thus, pose a threat to the validity of this approach. The present study focuses on modeling competencies in various domains, using data from a school sample (N = 15,396) and an adult sample (N = 7,256) from the National Educational Panel Study. Our interest was to investigate whether violations of unidimensionality and the normal distribution assumption severely affect the performance of the model-based approach in terms of differences in ability estimates. We propose a model with a competence dimension, a unidimensional missing propensity and a distributional assumption more flexible than a multivariate normal. Using this model for ability estimation results in different ability estimates compared with a model ignoring missing responses. Implications for ability estimation in large-scale assessments are discussed

Monetary Policy Transmission and House Prices: European Cross Country Evidence

This paper explores the importance of housing and mortgage market heterogeneity in 13 European countries for the transmission of monetary policy. We use a pooled VAR model which is estimated over the period 1995-2006 to generate impulse responses of key macroeconomic variables to a monetary policy shock. We split our sample of countries into two disjoint groups according to the impact of the monetary policy shock on real house prices. Our results suggest that in countries with a more pronounced reaction of real house prices the propagation of monetary policy shocks to macroeconomic variables is amplified