A parametric model fitting time to first event for overdispersed data: application to time to relapse in multiple sclerosis

In this article, we propose a parametric model for the distribution of time to first event when events are overdispersed and can be properly fitted by a Negative Binomial distribution. This is a very common situation in medical statistics, when the occurrence of events is summarized as a count for each patient and the simple Poisson model is not adequate to account for overdispersion of data. In this situation, studying the time of occurrence of the first event can be of interest. From the Negative Binomial distribution of counts, we derive a new parametric model for time to first event and apply it to fit the distribution of time to first relapse in multiple sclerosis (MS). We develop the regression model with methods for covariate estimation. We show that, as the Negative Binomial model properly fits relapse counts data, this new model matches quite perfectly the distribution of time to first relapse, as tested in two large datasets of MS patients. Finally we compare its performance, when fitting time to first relapse in MS, with other models widely used in survival analysis (the semiparametric Cox model and the parametric exponential, Weibull, log-logistic and log-normal models).     

Changes in union status during the transition to parenthood in eleven European countries, 1970s to early 2000s

Couples who have children are increasingly likely to have lived together without being married at some point in their relationship. Some couples begin their unions with cohabitation and marry before first conception, some marry during pregnancy or directly after the first birth, while others remain unmarried 3 years after the first birth. Using union and fertility histories since the 1970s for eleven countries, we examine whether women who have children in unions marry, and if so, at what stage in family formation. We also examine whether women who conceive when cohabiting are more likely to marry or separate. We find that patterns of union formation and childbearing develop along different trajectories across countries. In all countries, however, less than 40 per cent of women remained in cohabitation up to 3 years after the first birth, suggesting that marriage remains the predominant institution for raising children.     

Here or There? Shifting Meanings and Practices in Mother–Child Relationships across Time and Space

In this paper, I analyse the changes that mothers and children experience in their relationship due to the physical separations and reunions entailed by the international migration process. I argue that the different geographical configurations that migrant families take over time are the outcome of a negotiation of care responsibility and desired geographies of family life, and are accompanied by changing meanings and practices in intimate relationships: the location of care relationships is influenced by the relatives' capacity both to take part in family negotiations as well as to overcome the constraints imposed by policies. Time is relevant because it leads to shifting meanings and practices of transnational family life, as well as to the changing role of children in the family.     

Kuznets Prize for Makoto Hirazawa and Akira Yakita

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Kuznets Prize for Makoto Hirazawa and Akira Yakita     

DOES DIVORCE LAW MATTER?

In this paper we derive an explicit model of negotiations between spouses when unconstrained transfers are possible only in case of separation. We show that inefficient separation may occur in equilibrium even under consensual divorce law. This provides theoretical support for the view that changes in social norms rather than in legislation may be responsible for increasing divorce rates. (JEL: C78, J120)     

Technical Progress,Life of Capital and Employment

This paper examines the hypothesis of a quickening of capital replacement, triggered by the acceleration of technical progress. We present a microeconomic model of replacement processes inspired by the “unbalanced growth” school, highlighting the role of productivity in determining the growth path. The model distinguishes between two types of enterprise, stagnant and progressive, on the basis of productivity trends and shows that prolonged acceleration in the rate of technical progress may be sufficient reason for a rational entrepreneur to make replacements earlier, thus approaching a system of continuous restructuring. We then discuss the main theoretical implications for aggregate employment and the fundamental questions of measurability of the effects. To this end, we undertake an empirical test of aggregate data for the manufacturing sector in four leading economies (the United States, France, Germany, the United Kingdom) from 1970 to 1991. We estimate labour demand functions in which the traditional explanatory variables are supplemented by proxies that capture the effect of a shortening of the life of capital equipment (the replacement rate and the ratio between depreciation and gross fixed capital formation). The empirical evidence confirms the shortening of the average lifetime of capital and is consistent with the main implications of the microeconomic model. The results show, at least indirectly, a negative correlation between an increase in speed of technical progress and the growth of employment.     

The Role of Family Ties in the Labour Market. An Interpretation Based on Efficiency Wage Theory

By casual empiricism, it seems that many firms take explicit account of the family ties connecting workers, often hiring individuals belonging to the same family or passing jobs on from parents to their children. This paper makes an attempt to explain this behaviour by introducing the assumption of altruism within the family and supposing that agents maximize a family utility function rather than an individual one. This hypothesis has been almost ignored in the analysis of the relationship between employers and employees. The implications of this assumption in the efficiency wage models are explored: by employing members of the same family, firms can use a (credible) harsher threat — involving a sanction for all the family’s members in case of one member’s shirking — that allows them to pay a lower efficiency wage. On the other hand, workers who accept this agreement exchange a reduction in wage with an increase in their probability of being employed: this can be optimal in a situation of high unemployment. Moreover, the link between parents and children allows the firm to follow a strategy that solves the problem of an individual’s finite time horizon by its making use of the family’s reputation.     

Looking for the Best and Brightest? Deservingness Regimes in Italian Labour Migration Management

It is often maintained that contemporary foreign labour recruitment programs have taken an increasingly selective stance and that skills are increasingly crucial in granting migrants easier access and stronger welfare and residency rights in receiving countries. The paper provides a retrospective account of the evolution of Italian labour migration management, paying attention to the changing selection criteria reflected in some of its “front, back and side doors”. It will be shown that Italian labour migration management is increasingly embracing a bifurcated regime of deservingness. Despite some recent tentative signs of change towards an increased evaluation of high skills as a selection principle embedded into a competitiveness‐driven frame, over the last decades labour migration management has been largely dominated by the recruitment of a low‐skilled workforce. The paper discusses the emergence of a specific construction migrants’ deservingness placing Italy in a peculiar position in a European context.     

Parental Competence in Italy: A Comparison Between Italian and Immigrant Parents

The migration experience could influence parental competence perception in immigrant parents. Within this framework the current work focuses on immigrant parenthood and whether a family’s migratory path could lead parents to feel less competent in their parental roles. The aim of the present study is to analyze perceptions of parental competence and family routines among immigrant and Italian parents during the middle childhood stages. The results showed that immigrant parents perceive themselves as more competent than Italians. Immigrants also attribute more importance to the dimension of relational and regulatory routines in daily family life than do Italian parents. Professionals can use these findings to better understand how best to enhance practices and strategies appropriate to the complexity of these intercultural contexts.