Prior specification of neighbourhood and interaction structure in binary Markov random fields

We formulate a prior distribution for the energy function of stationary binary Markov random fields (MRFs) defined on a rectangular lattice. In the prior we assign distributions to all parts of the energy function. In particular we define priors for the neighbourhood structure of the MRF, what interactions to include in the model, and for potential values. We define a reversible jump Markov chain Monte Carlo (RJMCMC) procedure to simulate from the corresponding posterior distribution when conditioned to an observed scene. Thereby we are able to learn both the neighbourhood structure and the parametric form of the MRF from the observed scene. We circumvent evaluations of the intractable normalising constant of the MRF when running the RJMCMC algorithm by adopting a previously defined approximate auxiliary variable algorithm. We demonstrate the usefulness of our prior in two simulation examples and one real data example.     

Personal income taxation under mobility, exogenous and endogenous welfare weights, and asymmetric information

This paper analyses how governments should tax labour income accruing to a group of highly skilled and geographically mobile individuals who divide their time or career between several jurisdictions. The analysis differs from previous models on migration and taxation by addressing optimal regulation when agents work for several principals. Optimal taxation is developed for social welfare functions with exogenous and endogenous welfare weights. Marginal income taxes are applied for screening purposes, and the rates are lower with endogenous than with exogenous welfare weights. Received: 22 January 1998/Accepted: 3 July 1999)     

Risk Perceptions and Alcohol Consumption among Young People

Swedish cross-sectional survey data on young individuals was used to analyse the determinants of perceived risks of alcohol use and how these perceptions relate to drinking behaviour. Three major conclusions were drawn: (1) that people overestimate the risks of alcoholism, (2) that these risk perceptions fall substantially with age, but nevertheless imply risk overestimation, and (3) that education about alcohol, narcotics and tobacco leads individuals to perceive risks more correctly and to have lower risk beliefs. An additional finding was that individuals with higher perceived risks were less likely to consume alcohol. Equations were estimated both separately and simultaneously.     

‘Meeting Face to Face Creates New Insights’: Recruiting Persons with User Experiences as Students in an Educational Programme in Social Work

Even though empowerment and involvement of users have, for a long time, been important goals for educational programmes in social work, these programmes have only to a very little extent availed themselves of the resources that people with user experiences have to offer. This article will present a course that is part of the bachelor programmes in social work and social education at Lillehammer University College in Norway. Persons with user experiences were recruited and took part in a course on equal terms with the bachelor students. Four lecturers from the college, including the author as the project leader, carried out the planning and implementation of the course. The article gives an account of the experiences gained from the course as expressed by the students.     

Green giant or straw man? Environmental pressure and civil conflict, 1961–99

The proposition that environmental scarcity causes violent conflict attracts both popular and academic interest. Neomalthusian writers have developed theoretical arguments explaining this connection, and have conducted numerous case studies that seem to support the view that scarcity of biological assets such as land and other renewable resources causes conflict. So far there have been few systematic quantitative or comparative studies, and the few that exist have focused on particular forms of environmental degradation or on a small subset of resources, particularly mineral wealth. We test a more general argument about the effects of resource scarcity by examining the most widely-used measure of environmental sustainability: the ecological footprint. Contrary to neomalthusian thinking, we find that countries with a heavier footprint have a substantially greater chance of peace. Biocapacity and the ecological reserve also predict to peace, but these results are more fragile. Separate tests for smaller conflicts, for the post-Cold War period, and with additional control variables do not yield stronger support for the scarcity thesis. On the whole, the neomalthusian model of conflict receives little support from this analysis. We cannot exclude that erosion of the earth’s carrying capacity can increase conflict in the long run, but an empirical analysis with the ecological footprint measure does not provide any support for such a position.     

On the simple linear regression model with correlated measurement errors

The simple linear regression model with measurement error has been subject to much research. In this work we will focus on this model when the error in the explanatory variable is correlated with the error in the regression equation. Specifically, we are interested in the comparison between the ordinary errors-in-variables estimator of the regression coefficient β$\beta$ and the estimator that takes account of the correlation between the errors. Based on large sample approximations, we compare the estimators and find that the estimator that takes account of the correlation should be preferred in most situations. We also compare the estimators in small sample situations. This is done by stochastic simulation. The results show that the estimators behave quite similarly in most of the simulated situations, but that the ordinary errors-in-variables estimator performs considerably worse than the estimator that takes account of the correlation for certain parameter combinations. In addition, we look briefly into the bias introduced by ignoring correlated errors when computing sample correlations, and in predictions.     

Implementing human resource development best practices: Replication or re-creation?

Abstract

Firms increasingly introduce HRD ‘best practices’ developed somewhere else, but results often fall short of expectations. Much of existing theory fails to guide the implementation of HRD best practices because it does not recognize how introduced practices interact with existing practices in the firm. In this paper, we contrast the dominant perspective ‘Implementation as Replication’ with a perspective of ‘Implementation as Re-creation’. Through four stages of the implementation process, we identify and discuss how these contrasting perspectives yield different implications for how firms go about introducing HRD best practices. First, when firms take up a practice, is this a process of adoption or translation? Second, is it assumed that new knowledge can be implanted directly and lead to new behaviour, or is active experimentation a necessary precondition to gain new knowledge? Third, are deviations from the intended plan considered errors to be corrected or sources for learning? Fourth, are introduced best practices treated in isolation or as integral parts of the firm's management system? We argue that implementation efforts guided by the re-creation perspective increase the prospects of HRD best practices succeeding as a useful tool in the receiving firm.     

The health returns to schooling—what can we learn from twins?

This paper estimates the health returns to schooling, using a twin design. For this purpose, I use data on monozygotic twins from the Midlife in the United States survey. The results suggest that completing high school improves health, as measured through self-reported health, chronic conditions, and exercise behavior, but that additional schooling does not lead to additional health gains. Controlling for certain early life factors that may vary within twin pairs does not alter the main conclusions of this paper.     

The intergenerational transmission of human capital: the role of skills and health

We provide new evidence on some of the mechanisms reflected in the intergenerational transmission of human capital. Applying both an adoption and a twin design to rich data from the Swedish military enlistment, we show that greater parental education increases sons’ cognitive and non-cognitive skills, as well as their health. The estimates are in many cases similar across research designs and suggest that a substantial part of the effect of parental education on their young adult children’s human capital works through improving their skills and health.     

Modelling free social spaces and the diffusion of social mobilization

Free social spaces have long been emphasized in the social movement literature. Under names such as safe spaces, social havens, and counterpublics, they have been characterized as protective shelters against prevailing hegemonic ideologies and as hubs for the diffusion of ideas and ideologies. However, the vast literature on these spaces has predominantly focused on internal dynamics and processes, thus neglecting how they relate to the diffusion of collective mobilization. Inspired by formal modeling in collective action research, we develop a network model to investigate how the structural properties of free social spaces impact the diffusion of collective mobilization. Our results show that the assumption of clustering is enough for structural effects to emerge, and that clustering furthermore interacts synergistically with political deviance. This indicates that it is not only internal dynamics that play a role in the relevance of free social spaces for collective action. Our approach also illustrates how formal modeling can deepen our understanding of diffusion processes in collective mobilizations through analysis of emergent structural effects.