Bayesian networks for imputation

Summary.  Bayesian networks are particularly useful for dealing with high dimensional statistical problems. They allow a reduction in the complexity of the phenomenon under study by representing joint relationships between a set of variables through conditional relationships between subsets of these variables. Following Thibaudeau and Winkler we use Bayesian networks for imputing missing values. This method is introduced to deal with the problem of the consistency of imputed values: preservation of statistical relationships between variables ( statistical consistency ) and preservation of logical constraints in data ( logical consistency ). We perform some experiments on a subset of anonymous individual records from the 1991 UK population census.     

An experimental investigation of the impact of ambiguity on the valuationof self-insurance and self-protection

We build two experimental markets to examine individual valuations of risk reductions with two risk-management tools: self-insurance and self-protection. We find no positive evidence that the risk-reducing mechanisms constitute a “frame.” Ambiguity in the probability on average affects valuation only weakly, and changes in the representation of ambiguity do not alter valuation. Finally, unlike the results obtained by Hogarth and Kunreuther for the case of market insurance, our findings do not provide a strong support for the “Anchoring and Adjustment” ambiguity model.     

See you on Facebook! A framework for analyzing the role of computer-mediated interaction in the evolution of social capital

Empirical studies have documented a decline in indicators of social participation in the last five decades. The responsibility of social disengagement has often been attributed to pervasive busyness and the increasing pressure on time. In this paper we argue that computer-mediated interaction, and particularly online networking, can help mitigate this downward trend. We develop a logical framework for assessing the role of the Internet in the evolution of social participation. We analyze an economy where agents can develop their social interactions through two main modes of participation, one encompassing both online networking and face to face interactions, and the other solely based on physical encounters. We study the interdependence between the increase in the pressure on time and the variation in the relative performance of the two strategies of participation.     

The Multidimensionality of Child Poverty: Evidence from Afghanistan

This paper examines multidimensional poverty among children in Afghanistan using the Alkire-Foster method. Several previous studies have underlined the need to separate children from their adult nexus when studying poverty and treat them according to their own specificities. From the capability approach, child poverty is understood to be the lack of freedom to do and to be what children themselves value and have reason to value. The case of Afghanistan is particularly relevant as years of conflict aggravated by several severe droughts, political insecurity, bad governance and ongoing violence have significantly increased poverty in the country. The paper discusses the relevant dimensions when analysing child poverty and uses data from a survey carried out by Handicap International which contains information on dimensions of children’s wellbeing that is typically missing in standard surveys. Ten dimension are considered in this paper: health, care and love, material deprivation, food security, social inclusion, education, freedom from economic and non-economic exploitation, shelter and environment, autonomy, and mobility. Our results show that younger children, those living in rural areas, girls and disabled children are the most deprived.     

The effects of separate taxation on labor participation of married couples. An empirical analysis using propensity score

Up to 1987 the Spanish Income Tax imposed compulsory joint filing for married couples. However, the 1988 reform allowed spouses to choose between joint and separate taxation, involving a reduction in tax rates for secondary earners. Our aim is to analyze this reform as a quasi-natural experiment, assessing the effects of tax changes on labor participation. To find out the causal effect we adopt the difference-in-differences technique. We use data from the ‘Spanish Income Tax Panel 1982–1998’. Our results show that, as a consequence of differential tax changes, married women in families more strongly affected by the fiscal reform increase their labor participation more than secondary earners from families less affected by the reform. The participation rate for secondary earners in the treatment group increases by 9.4 percentage points whereas the control group increases their participation rate by 7.8 percentage points. We define the treatment group as those secondary earners in relatively low-income families in year 1987 and the control group as those in middle-high income families, because the former experiences a stronger reduction in tax rates than the latter. As a result, we can attribute the 1.6-percentage-point-increase in participation rates to the 1988 income tax reform.     

Does the capital of social capital matter? Relational resources of the board and the performance of Brazilian companies

Based on theories of social capital, in this study, we seek to assess the impact of a board’s social capital on the market value of companies listed on the Brazilian stock exchange. As our indicator of social capital, we use the relational resources identified in the direct, indirect and heterogeneous ties of the board. Employing panel data from 508 observations, our results indicate that heterogeneous relational resources have a stronger and more significant influence than the resources available from board members’ direct relationships. Additionally, as the effects of board interlock are endogenously determined by several factors related to the firm level, we seek to mitigate the endogeneity problem using models of instrumental variables and simultaneous equations. Our hypotheses were consistent after controlling for endogeneity. We also check whether the board’s social capital could present a U-inverted effect on the market value. This relationship was only plausible in social capital by indirect ties. Finally, we isolate the effect of relational resources within and between industries on Tobin’s Q. There was no significant effect through interlocks within the same industry. However, ties with companies in several other industries were significant.     

Ergonomic factors and production target evaluation in eucalyptus timber harvesting operations in mountainous terrains

There are several forest operations involved in Eucalyptus timber harvesting. This study was carried out during brush-cutting; tree felling, bucking, delimbing, piling and manual extraction operations, with the following objectives: a) analyzing, ergonomically, two systems of brush-cutting: one manual and the other semi-mechanized, using two different machines; b) ergonomically evaluating three different brands of pruner machines used in delimbing felled trees. c) determining the feasible target of productivity as a function of ergonomic factors relevant to establish the time of resting pauses for workers in manual and semi-mechanized timber harvesting systems in mountainous terrain. Brush-cutting, either manual or semimechanized, is an activity carried out prior to timber harvesting. It is usually a hard work, with low productivity when compared with mechanized systems. Pruner machines have been used by forest companies, due to the great possibilities to improve productivity, quality and the health of workers. Ergonomics is a discipline that promotes the adequacy of work to the physical and mental characteristics of human beings, seeking to design production systems and products considering relevant aspects, including social, organizational and environmental factors. Companies should consider the ergonomic factor in the determination of daily worker production targets.     

Are the Competent the Morally Good? Perspective Taking and Moral Motivation of Children Involved in Bullying

The present study tested the hypothesis of the cognitively competent but morally insensitive bully. On the basis of teacher and peer ratings, 212 young elementary school children were selected and categorized as bullies, bully–victims, victims, and prosocial children. Children's perspective-taking skills were assessed using theory-of-mind tasks, and moral motivation was assessed with a task about moral emotion attributions after moral rule transgressions. Analyses at the group level revealed that only bully–victims, but not bullies, were characterized by a deficit in perspective taking, while both aggressive groups showed a deficit in moral motivation. Analyses at the individual level, however, revealed that bullies were a more heterogeneous group, including children with an asymmetry between perspective taking and moral motivation, as well as children scoring consistently low or high on both measures. The findings highlight the importance of distinguishing between (1) strategic social–cognitive and moral competencies and (2) different subgroups of bullies.