Analysis of a long-term study of neurotic disorder, with insights into the process of non-response

Summary.  The paper studies the non-response process in a long-term study of neurotic dis-order by comparing the analysis based on the responses that were collected by the established practice of interviewing the subjects, at dates arranged in advance (appointments), with the analysis of the nearly complete set of responses that were collected by an extensive effort that involved attempts to interview without seeking a prior agreement. The method of multiple imputation is applied, and its properties are explored in a setting that is not perfectly suited for its application: a relatively small sample size, ordinal score outcomes and the likelihood that the outcomes are missing not at random.     

Rail infrastructure charging in Hellenic railways

In this paper we consider marginal cost estimation in Greek railways over the period 2000-2004. Marginal cost estimation has been recently an active area of research when disaggregated data by line of operation are available but factor price data are not available. We propose panel data techniques to deal with the problem of statistical efficiency of parameters estimators. Our estimates show that marginal cost in Greek railways is comparable to the estimates in other European countries.     

Taking a "Hands On" Approach to Diversity in Higher Education: A Critical-Dialogic Model for Effective Intergroup Interaction

This article reviews divergent empirical evidence on interracial contact. While research on diversity in higher education provides ample evidence for the educational benefits of engaging with diversity in informal interactions or courses, experimental and naturalistic studies in social psychology on interracial interactions reveal a complicated picture, showing what appear to be both positive and negative effects. Rather than addressing the question of whether or not to promote interracial interactions on campus, we present a critical-dialogic model of intergroup dialogue that centers on communication processes as an avenue toward intergroup relationships, understanding, and collaboration. Prior research and preliminary results from a nine-university research collaboration provide strong empirical support for the proposed model. We conclude with program and policy considerations for higher education institutions interested in promoting meaningful intergroup interaction.     

Bayesian Instrumental Variables: Priors and Likelihoods

Instrumental variable (IV) regression provides a number of statistical challenges due to the shape of the likelihood. We review the main Bayesian literature on instrumental variables and highlight these pathologies. We discuss Jeffreys priors, the connection to the errors-in-the-variables problems and more general error distributions. We propose, as an alternative to the inverted Wishart prior, a new Cholesky-based prior for the covariance matrix of the errors in IV regressions. We argue that this prior is more flexible and more robust thanthe inverted Wishart prior since it is not based on only one tightness parameter and therefore can be more informative about certain components of the covariance matrix and less informative about others. We show how prior-posterior inference can be formulated in a Gibbs sampler and compare its performance in the weak instruments case for synthetic as well as two illustrations based on well-known real data.     

Making a connection: school engagement of young people in care

Intervention to improve educational attainment for children in out‐of‐home care is increasingly being recognized as important for their well‐being and future opportunities. This paper reports on a mixed method study of the school engagement or connectedness of young people in care. The study comprised a survey of 202 young people in care in Queensland, Australia, and a matched comparison group of young people not in care, plus interviews with a subset of 65 young people in care who were surveyed. Both the school environment and the perceived levels of support influenced school engagement, with those who were assisted by carers and caseworkers more likely to be positively connected with school. These young people perceived education as a pathway to achieving work and life goals. The findings suggest that active and focused attention on young people's school engagement should be part of case planning and monitoring as it offers an additional strategy for improving their educational experience.     

A Causal Analysis of Large Vehicle Accidents Through Fault-Tree Analysis

Recent trends indicate that vehicle miles traveled for large trucks is increasing at a higher rate than for other vehicles. The resulting competition between large trucks and other vehicles for highway space can be expected to result in more multivehicle collisions involving large trucks. This paper presents the result of an investigation of the causes and the mechanism related to large vehicle accidents. A fault-tree analysis of large vehicle accidents identifies the individual roles played by driver, vehicle, and environmental factors, as well as their interactions in the accident mechanism. Using accident data for 1984-1986, the probabilities for different basic events in the fault tree were assessed. The most likely events leading to a large vehicle accident, as well as the most effective counter measures, were then identified. The result indicate that the most prevalent form of accidents due to driver-related failures is when a normal driver makes an error in judgment and is unsuccessful in his or her evasive action. For vehicle-related failures, the predominant type of failure is equipment failure, and for environmental-related failures, excessive demand on driver and vehicle performance created by the environmental or roadway factors.     

Marker processes in survival analysis

In the development of many diseases there are often associated variables which continuously measure the progress of an individual towards the final expression of the disease (failure). Such variables are stochastic processes, here called marker processes, and, at a given point in time, they may provide information about the current hazard and subsequently on the remaining time to failure. Here we consider a simple additive model for the relationship between the hazard function at time t and the history of the marker process up until time t. We develop some basic calculations based on this model. Interest is focused on statistical applications for markers related to estimation of the survival distribution of time to failure, including (i) the use of markers as surrogate responses for failure with censored data, and (ii) the use of markers as predictors of the time elapsed since onset of a survival process in prevalent individuals. Particular attention is directed to potential gains in efficiency incurred by using marker process information.     

Book reviews

Qualitative Sociology -