A Mixed Model-assisted Regression Estimator that Uses Variables Employed at the Design Stage

The Generalized regression estimator (GREG) of a finite population mean or total has been shown to be asymptotically optimal when the working linear regression model upon which it is based includes variables related to the sampling design. In this paper a regression estimator assisted by a linear mixed superpopulation model is proposed. It accounts for the extra information coming from the design in the random component of the model and saves degrees of freedom in finite sample estimation. This procedure combines the larger asymptotic efficiency of the optimal estimator and the greater finite sample stability of the GREG. Design based properties of the proposed estimator are discussed and a small simulation study is conducted to explore its finite sample performance.     

Increased risk of emergency department presentations for bronchiolitis in infants exposed to air pollution

Air pollution has been linked to an increased risk of several respiratory diseases in children, especially respiratory tract infections. The present study aims to evaluate the association between pediatric emergency department (PED) presentations for bronchiolitis and air pollution. PED presentations due to bronchiolitis in children aged less than 1 year were retrospectively collected from 2007 to 2018 in Padova, Italy, together with daily environmental data. A conditional logistic regression based on a time-stratified case-crossover design was performed to evaluate the association between PED presentations and exposure to NO₂, PM2.5, and PM10. Models were adjusted for temperature, relative humidity, atmospheric pressure, and public holidays. Delayed effects in time were evaluated using distributed lag non-linear models. Odds ratio for lagged exposure from 0 to 14 days were obtained. Overall, 2251 children presented to the PED for bronchiolitis. Infants’ exposure to higher concentrations of PM10 and PM2.5 in the 5 days before the presentation to the PED increased the risk of accessing the PED by more than 10%, whereas high concentrations of NO₂ between 2 and 12 days before the PED presentation were associated with an increased risk of up to 30%. The association between pollutants and infants who required hospitalization was even greater. A cumulative effect of NO₂ among the 2 weeks preceding the presentation was also observed. In summary, PM and NO₂ concentrations are associated with PED presentations and hospitalizations for bronchiolitis. Exposure of infants to air pollution could damage the respiratory tract mucosa, facilitating viral infections and exacerbating symptoms.     

Time as a limited resource: Communication strategy in mobile phone networks

We used a large database of 9 billion calls from 20 million mobile users to examine the relationships between aggregated time spent on the phone, personal network size, tie strength and the way in which users distributed their limited time across their network (disparity). Compared to those with smaller networks, those with large networks did not devote proportionally more time to communication and had on average weaker ties (as measured by time spent communicating). Further, there were not substantially different levels of disparity between individuals, in that mobile users tend to distribute their time very unevenly across their network, with a large proportion of calls going to a small number of individuals. Together, these results suggest that there are time constraints which limit tie strength in large personal networks, and that even high levels of mobile communication do not fundamentally alter the disparity of time allocation across networks.     

Electing a parliament

We present a model where a society elects candidates belonging to two parties to a national parliament. The electoral rule determines the seats distribution between the two parties. The policy outcome is a function of the number of seats the two parties win in the election. We analyze two electoral rules, multidistrict majority and single district proportional. We prove that under both systems there is a unique pure strategy perfect equilibrium outcome. We compare the outcomes under the two systems.     

The effect of corporate governance on sustainability disclosure

Drawing on stakeholder theory, this paper examines the relationship of board composition, leadership and structure on sustainability disclosure. We discuss that good corporate governance and sustainability disclosure can be seen as complementary mechanisms of legitimacy that companies may use to dialogue with stakeholders. Specifically we claim that, as disclosure policies emanate from the board of directors, sustainability disclosure may be a function of the board attributes: we investigate the relationship between different characteristics of the board and sustainability disclosures among US and European companies. Our results show that in order to explain the effect of board composition on sustainability disclosure we need to go beyond the narrow and traditional distinction between insider and independent directors, focusing on the specific characteristics of each director.     

Measurement of the quality of family planning services

The quality of health services is a subject of increasing interest to health care providers and organizations responsible for financing and promoting health services. The importance of the client's perspective (and by inference, the perspective of potential clients, as well) is now well established, but efforts to define and measure quality have thus far been limited to the perspective of experts even when the experts claim to speak for the clients. In this paper we utilize family planning programs to explore issues of the quality of health services. We propose that a better understanding of the view of quality actually held by family planning program clients will clarify the influence of quality on the use of services, a clarity that has not been possible by looking at quality only as defined by providers, managers or experts. We review the literature on quality of services and identify the gaps in research that must be filled if a better understanding of what quality is and how it relates to service outcomes is to be obtained. A first step must be the research required to develop a set of measures of quality that reflects the multi-dimensional nature of quality, includes the clients' view of services in the definition of quality, and incorporates methodologies required to ascertain the true view of clients. Finally, we suggest that dimensions of quality identified as important for clients as a group will be more predictive of use of services than dimensions identified as important to providers.     

Innovation in Family Firms: A Systematic Literature Review and Guidance for Future Research

Through a systematic review of 118 peer‐reviewed journal articles published between 1961 and 2017, this article provides an integrative picture of the state of the art of the family firm innovation literature. Our aim is to widen existing understanding of innovation in family firms by building a theoretical bridge with studies in the mainstream innovation literature. Specifically, in identifying the main gaps in the literature and providing future research directions, our critical and dynamic picture of family‐specific determinants of innovation is intended to advance the debate on innovation in general, and family firms in particular.     

Why the rise in adolescent fertility rates in the Dominican Republic in the 1990s?

Despite concern over high pregnancy rates and levels of risk for sexually transmittedinfections, adolescent fertility rates in the Dominican Republic have not changed substantially since the early 1980's, and actually increased during the early to mid 1990s. The present study was undertaken to assess the factors contributing to the recent rise in fertility among Dominican adolescents. The findings suggest that although contraceptive use among adolescents and young adults has increased, this has been more than offset by ominous trends on other determinants of fertility. Among these are declines in mean age at first sex and first marriage/union without a commensurate decline in mean age at first contraceptive use, and stubbornly high discontinuation rates for oral contraceptives andcondoms. There is also some evidence that rates of induced abortion among adolescents may have increased, without which adolescent fertility rates would have been even higher. Demand for children among Dominican adolescents remains strong, suggesting that efforts to reduce the current high prevalence of risky sexual behaviors need to influence social norms in order to be successful.