Tribute to Jean-Yves Jaffray

Tribute to Jean-Yves Jaffray by the French Group of Decision Theory.     

On the historical determinants of third sector strength: A qualitative comparative analysis

This study proposes a theoretical explanation for the main causes of the third sector's strength. A Boolean comparative analysis based mainly on the theoretical frameworks of Rokkan and Esping-Andersen indicates that the combination of state-supported urban interests and Protestantism are necessary conditions. This result is very close to Max Weber's explanation of civil society which presupposes the facilitating role of the autonomous state. Thus, the empirical results are reinterpreted within the context of a Weberian explanatory framework. The implications of this endeavor within the historical context of developing countries are further explicated.     

Lower bounds and a tabu search algorithm for the minimum deficiency problem

An edge coloring of a graph G=(V,E) is a function c:E→ℕ that assigns a color c(e) to each edge e∈E such that c(e)≠c(e′) whenever e and e′ have a common endpoint. Denoting S _v (G,c) the set of colors assigned to the edges incident to a vertex v∈V, and D _v (G,c) the minimum number of integers which must be added to S _v (G,c) to form an interval, the deficiency D(G,c) of an edge coloring c is defined as the sum ∑ _v∈V D _v (G,c), and the span of c is the number of colors used in c. The problem of finding, for a given graph, an edge coloring with a minimum deficiency is NP-hard. We give new lower bounds on the minimum deficiency of an edge coloring and on the span of edge colorings with minimum deficiency. We also propose a tabu search algorithm to solve the minimum deficiency problem and report experiments on various graph instances, some of them having a known optimal deficiency.     

Gender homophily from spatial behavior in a primary school: A sociometric study

We investigate gender homophily in the spatial proximity of children (6–12 years old) in a French primary school, using time-resolved data on face-to-face proximity recorded by means of wearable sensors. For strong ties, i.e., for pairs of children who interact more than a defined threshold, we find statistical evidence of gender preference that increases with grade. For weak ties, conversely, gender homophily is negatively correlated with grade for girls, and positively correlated with grade for boys. This different evolution with grade of weak and strong ties exposes a contrasted picture of gender homophily.     

Inequality decomposition values: the trade-off between marginality and efficiency

This paper presents a general procedure for decomposing income inequality measures by income sources. The methods of decomposition proposed are based on the Shapley value and extensions of the Shapley value of transferable utility cooperative games. In particular, we find that Owen’s value can find an interesting application in this context.We show that the axiomatization by the potential of Hart and Mas-Colell remains valid in the presence of the domain restriction of inequality indices. We also examine the properties of these decomposition rules and perform a comparison with Shorrocks’ decomposition rule properties.     

Will they stay or will they go? How network properties of WebICs predict dropout rates of valuable Wikipedians

This paper contributes to our understanding of an increasingly prevalent work system, web-based internet communities (WebICs). We are particularly interested in how WebICs are governed given the fact how different they are compared to more classical forms of organization. We study the governance of a WebIC by studying the structure and dynamics of their edit network. Given the fact that the edit network is a relational structure, social network analysis is key to understanding these work systems. We demonstrate that characteristics of the edit network contribute to predicting the dropout hazard of valuable WebIC members. Since WebICs exist only thanks to the activity of their contributors, predicting drop-outs becomes crucial. The results show that reputation and controversy have different effects for different types of Wikipedians; i.e., an actor’s reputation decreases the dropout hazard of active Wikipedians, while participation on controversial pages decreases the dropout hazard of highly active Wikipedians.     

Network influence and organizational performance: The effects of tie strength and structural equivalence

We combine theory and empirical evidence to develop and test three related claims about how ties strength and structural equivalence affect interorganizational performance similarity. First, network partners attain similar levels of performance because direct network ties facilitate information and resource sharing, and the diffusion of organizational practices. Organizations occupying similar network positions attain similar levels of performance because they face similar competitive constraints. Second, because mechanisms underlying performance similarity implied by direct network ties and similarity in network positions are different, strength of network ties and network position affect different dimensions of organizational performance. Third, we expect that tie strength will affect aspects of performance that are more likely to be influenced by processes activated by the direct contact between network partners. We expect structural equivalence to affect more strongly those aspects of organizational performance that are more directly influenced by competition. An analysis of interorganizational networks and organizational performance within a regional community of hospitals provides evidence in support of these claims. Models estimated on a sample of 8190 interorganizational dyads suggest that the effects of tie strength and structural equivalence on organizational performance are highly differentiated and contingent on specific aspects of performance. We show that these conclusions are robust with respect to a wide variety of other factors that may be responsible for performance similarity including competitive interdependence, structural homophily, and resource complementarity.     

How do actors shape social networks during the process of new product development?

Recent studies on new-idea generation and development have highlighted the role played by network structure in the genesis of new combinations or the process of selecting ideas. However, less attention has been paid to the factors that entice actors to shape social networks during the process of the development of new ideas.This research was conducted in an R&D facility of a semi-conductor company. We analysed the generation of five creative projects and their development over a four-year period. We used a longitudinal approach and collected data through interviews and observations to identify the creative contributions and the actors who were involved at different time periods for each project. We mapped the relationships between actors who contributed to the development of each idea through creative thinking and/or helped it to become accepted both internally and externally over three-year windows. This method generated data on network evolution.We also carried out a qualitative analysis and identified four main factors explaining why actors turn to others during the idea-development process: (1) to gain access to information; (2) to enhance credibility; (3) to exercise one’s influence; and (4) to gain access to knowledge through people or objects. We demonstrate that different types of ties or network structures are relied upon to reap different kinds of benefits. This may partially explain network evolution as an idea progresses through different development stages.     

The mediating role of work-to-family conflict in the relationship between shiftwork and depression

Abstract

With significant segments of the working population involved in shiftwork, there is the possibility of serious health outcomes. There are two possible pathways to ill health. In the biological pathway the body's circadian rhythms are affected, leading to physiological disturbances and the inability to cope. By contrast, the aim of this study is to elucidate a social pathway by which shiftwork may lead to mental ill health. It examines the mediating influence of work-to-family conflict in the association between shiftwork and depression. Gender differences are also investigated. The sample included 2,931 Canadian respondents with a spouse and at least one child living at home. Close to 28% of respondents were involved in some form of shiftwork. Structural equation modelling supported partial mediation through work-to-family conflict. Further analyses found that mediation was supported in sub-samples of male and female respondents. The results, however, suggest that the experience of shiftwork is quite similar for men and women as no significant differences were found between mediating models. Overall, the findings support the social explanation of the effect of shiftwork on mental health, but they do not rule out other social or biological pathways.