Time-varying autoregressive conditional duration model

The main goal of this work is to generalize the autoregressive conditional duration (ACD) model applied to times between trades to the case of time-varying parameters. The use of wavelets allows that parameters vary through time and makes possible the modeling of non-stationary processes without preliminary data transformations. The time-varying ACD model estimation was done by maximum-likelihood with standard exponential distributed errors. The properties of the estimators were assessed via bootstrap. We present a simulation exercise for a non-stationary process and an empirical application to a real series, namely the TELEMAR stock. Diagnostic and goodness of fit analysis suggest that the time-varying ACD model simultaneously modeled the dependence between durations, intra-day seasonality and volatility.     

Firm-level social returns to education

Do workers benefit from the education of their co-workers? We examine this question first by introducing a model of learning, which argues that educated workers may transfer part of their general skills to uneducated workers, and then by examining detailed matched employer–employee panel data from Portugal. We find evidence of large firm-level social returns (between 14% and 23%), much larger than standard estimates of private returns, and of significant returns accruing to less educated workers but not to their more educated colleagues.     

The inverse weighted Lindley distribution: Properties,estimation and an application on a failure time data

In this paper a new distribution is proposed. This new model provides more flexibility to modeling data with upside-down bathtub hazard rate function. A significant account of mathematical properties of the new distribution is presented. The maximum likelihood estimators for the parameters in the presence of complete and censored data are presented. Two corrective approaches are considered to derive modified estimators that are bias-free to second order. A numerical simulation is carried out to examine the efficiency of the bias correction. Finally, an application using a real data set is presented in order to illustrate our proposed distribution.     

Bayesian spatio‐temporal models based on discrete convolutions

Abstract: The authors consider a class of models for spatio‐temporal processes based on convolving independent processes with a discrete kernel that is represented by a lower triangular matrix. They study two families of models. In the first one, spatial Gaussian processes with isotropic correlations are convoluted with a kernel that provides temporal dependencies. In the second family, AR(p) processes are convoluted with a kernel providing spatial interactions. The covariance structures associated with these two families are quite rich. Their covariance functions that are stationary and separable in space and time as well as time dependent nonseparable and nonisotropic ones.     

Immigrant perceptions of ethnic and racial discrimination: patterns and singularities in a municipality in the Lisbon Metropolitan Area

In Portugal, studies on discrimination against immigrants have focused almost exclusively either on the indigenous population, or on the foreign population. The former have tended to deploy quantitative and extended methodologies, while the latter studies have opted predominantly for qualitative or intensive methodologies, focusing on particular groups. There are few studies in which the immigrant population is extensively surveyed, covering its diverse origins, life trajectories, and social position in the host society.

In this analysis we examine the main factors that shape the perceptions of ethnic and racial discrimination among immigrant groups living in the Oeiras municipality in the Lisbon Metropolitan Area. This analysis is based on a quantitative analysis of a survey of 422 immigrants, of whom approximately half reported having been discriminated against since their arrival in Portugal. The study is focused on three main explanations related to predictive variables: sociographic, acculturation/cultural proximity, and opportunities for contact with the autochthonous population. A multivariate logistic regression demonstrates that there is a statistically significant relationship between perceived discrimination and some sociographic variables including cultural proximity, especially for Brazilians.     

A Dyadic Approach to Understanding the Link Between Sexual Functioning and Sexual Satisfaction in Heterosexual Couples

Researchers have demonstrated that several dimensions of sexual functioning (e.g., sexual desire, arousal, orgasm) are associated with the sexual satisfaction of individuals in a committed mixed-sex (male–female) relationship. We extended this research by comparing a dyadic model that included both own (i.e., actor effect) and partner (i.e., partner effect) domains of sexual functioning to an individual model that included only actor effects. Participants were 124 mixed-sex couples who completed online measures of sexual functioning and sexual satisfaction. Data analysis using the actor–partner interdependence model (APIM) and structural equation modeling (SEM) indicated that the dyadic model had a better fit than the individual model. Women’s sexual desire and orgasm and men’s erectile functioning were significant positive predictors of both own and partner’s sexual satisfaction. These results are discussed in terms of the importance of taking a dyadic approach to research and clinical work related to sexual satisfaction.     

Inheritances and wealth inequality: a machine learning approach

This paper explores the relationship between received inheritances and the distribution of wealth (financial, non-financial and total) in four developed countries: the United States, Canada, Italy and Spain. We follow the inequality of opportunity (IOp) literature and???considering inheritances as the only circumstance? we show that traditional IOp approaches can lead to non-robust and arbitrary measures of IOp depending on discretionary cut-off choices of a continuous circumstance such as inheritances. To overcome this limitation, we apply Machine Learning methods (‘random forest’ algorithm) to optimize the choice of cut-offs and we find that IOp explains over 60% of wealth inequality in the US and Spain (using the Gini coefficient), and more than 40% in Italy and Canada. Including parental education as an additional circumstance ?available for the US and Italy? we find that inheritances are still the main contributor. Finally, using the S-Gini index with different parameters to weight different parts of the distribution, we find that the effect of inheritances is more prominent at the middle of the wealth distribution, while parental education is more important for the asset-poor.

     

A self-comfort oriented pattern of regulatory behavior and avoidant attachment are more likely among infants born moderate-to-late preterm

Infants born preterm (<37 gestational weeks, GW) are at increased risk for regulatory difficulties and insecure attachment. However, the association between infants' regulatory behavior patterns and their later attachment organization is understudied in the preterm population. We addressed this gap by utilizing a Portuguese sample of 202 mother–infant dyads. Specifically, we compared the regulatory behavior patterns of 74 infants born moderate-to-late preterm (MLPT, 32–36 GW) to those of 128 infants born full-term (FT, 37–42 GW) and evaluated the associations of these regulatory patterns with later attachment. Infants' regulatory behavior patterns (Social-Positive Oriented, Distressed-Inconsolable, or Self-Comfort Oriented) were evaluated in the Face-to-Face-Still-Face paradigm at 3 months, and their attachment organization (secure, insecure-avoidant, or insecure-ambivalent) was evaluated in the Strange Situation at 12 months corrected age. In both samples, the Social-Positive-Oriented regulatory pattern was associated with secure attachment; the Distressed-Inconsolable pattern with insecure-ambivalent attachment; and the Self-Comfort-Oriented pattern with insecure-avoidant attachment. However, compared to FT infants, infants born MLPT were more likely to exhibit a Self-Comfort-Oriented pattern and avoidant attachment. Most perinatal and demographic variables were not related to infant outcomes. However, infants with a higher 1-min Apgar were more likely to exhibit the Social-Positive-Oriented regulatory pattern and secure attachment.     

Production Inflexibilities and the Cost Channel of Monetary Policy

This article shows how the existence of production inflexibilities in the form of capacity utilization constraints conditions the magnitude of the response of macroeconomic variables to a money supply stimulus. Capacity is modeled under explicit microfoundations, where the existence of idiosyncratic demand uncertainty generates variable utilization rates across firms. In this context, money has real effects due to non-Fisherian effects stemming from limitations in households' access to the financial market. Firms' capacity constraints generate a convex aggregate supply curve, which is a feature of the economy that has important implications for the conduct of monetary policy.     

Recycling the idea of race: socio-political agenda,transnational business culture,and diversity management in Brazil

ABSTRACT

This article intends to contribute to the line of studies that critically addresses diversity management, bringing the Brazilian experience into the discussion. It aims to demonstrate how large Brazilian companies and transnational corporations operating in the country have been recycling the idea of race in order to cope with the greatest politicisation of debates on the racial issue within the Brazilian public sphere since the late twentieth century. This phenomenon is related to changes in the political actions of the black movement in Brazil, which since the same period has been absorbing the new socio-political agenda existing within the global network of anti-racism advocacy. This is an agenda in which two purposes have a central importance: the battle against racial inequality and the demand for affirmative action policies. The data presented in this paper are part of broader research in which, by means of the biographical method and the ethnographic fieldwork, the social trajectories and career paths of two generations of Brazilian black executives were analysed.