A-optimal designs for heteroscedastic multifactor regression models

Abstract

This paper searches for A-optimal designs for Kronecker product and additive regression models when the errors are heteroscedastic. Sufficient conditions are given so that A-optimal designs for the multifactor models can be built from A-optimal designs for their sub-models with a single factor. The results of an efficiency study carried out to check the adequacy of the products of optimal designs for uni-factor marginal models when these are used to estimate different multi-factor models are also reported.     

LINGUISTIC DIVERSITY AND REDISTRIBUTION

This paper investigates the effect of linguistic diversity on redistribution in a broad cross‐section of countries. We use the notion of “linguistic distances” and show that the commonly used fractionalization index, which ignores linguistic distances, yields insignificant results. However, once distances between languages are accounted for, linguistic diversity has both a statistically and economically significant effect on redistribution. With an average level of redistribution of 9.5% of GDP in our data set, an increase byone standard deviation in the degree of diversity lowers redistribution by approximately one percentage point. We also demonstrate that other measures, such as polarization and peripheral heterogeneity, provide similar results when linguistic distances are incorporated. (JEL: D6, D74, H5, Z10)     

Developing a best practice model of refugee maternity care

BackgroundAbout one third of refugee and humanitarian entrants to Australia are women age 12–44 years. Pregnant women from refugee backgrounds may have been exposed to a range of medical and psychosocial issues that can impact maternal, fetal and neonatal health.Research questionWhat are the key elements that characterise a best practice model of maternity care for women from refugee backgrounds? This paper outlines the findings of a project which aimed at developing such a model at a major maternity hospital in Brisbane, Australia.Participants and methodsThis multifaceted project included a literature review, consultations with key stakeholders, a chart audit of hospital use by African-born women in 2006 that included their obstetric outcomes, a survey of 23 African-born women who gave birth at the hospital in 2007–08, and a survey of 168 hospital staff members.ResultsThe maternity chart audit identified complex medical and social histories among the women, including anaemia, female circumcision, hepatitis B, thrombocytopenia, and barriers to access antenatal care. The rates of caesarean sections and obstetric complications increased over time. Women and hospital staff surveys indicated the need for adequate interpreting services, education programs for women regarding antenatal and postnatal care, and professional development for health care staff to enhance cultural responsiveness.Discussion and conclusionsThe findings point towards the need for a model of refugee maternity care that comprises continuity of carer, quality interpreter services, educational strategies for both women and healthcare professionals, and the provision of psychosocial support to women from refugee backgrounds.     

Small mammal assemblages in fragmented shrublands of urban areas of Central Chile

Mediterranean-type ecosystems are one of the most affected environments by habitat loss and fragmentation due to urban development, however only few studies have evaluated the effects of urbanization on the biodiversity of remnant fragments in these ecosystems. This study aims to evaluate the effects of urban development over small mammal assemblages inhabiting isolated forest fragments of an urban area of Chilean Mediterranean zone. We compared abundance and richness of small mammal assemblages of six remnant fragments within an urban matrix, and six fragments similar in area and habitat characteristics with those of urban area, but surrounded by a rural matrix. We found that small mammal assemblages differ considerably among fragments types (urban vs rural), with lack of endemic species from urban fragments and with high proportion of introduced rodents in urban fragments. Furthermore abundance of small mammals was higher in rural than in urban fragments. In urban areas small mammal abundance and richness were not correlated with any of the explanatory variables assessed (woody cover, flora heterogeneity, fragment area, perimeter/area ratio). However in rural fragments small mammal richness was negatively correlated with flora heterogeneity and the abundance of small mammals was positively correlated with perimeter/area ratio. These results reveal important differences within the effects of fragmentation over small mammal assemblages among the two types of fragments assessed. Our findings suggest that in forest fragments isolated by urbanization, larger areas with good quality habitats are not sufficient to maintain native small mammal population.     

SPORTING EVENTS,EMOTIONAL CUES,AND CRIME: SPATIAL AND TEMPORAL EVIDENCE FROM BRAZILIAN SOCCER GAMES

Utilizing a novel data set of police reports that provides granular street‐ and vehicle‐level information on vehicle thefts and robberies in the city of São Paulo, Brazil, we explore the impact of soccer games and their outcomes on crime and study its spatial heterogeneity. Estimates from a regression discontinuity design suggest that crime increases immediately after home games in streets that are within a tight radius from the stadiums. The effect is driven by vehicle thefts with popular car models being more likely to be targeted and is particularly salient after upset losses and derby games.(JEL D91, R12, Z2)     

Mapping the Field of Donation-Based Crowdfunding for Charitable Causes: Systematic Review and Conceptual Framework

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This study compiles the main findings in the field of academic research on pure donation-based crowdfunding (DCF)...     

A spatial model of political competition and proportional representation

 A spatial model of party competition is studied in which: (i) Parties are supposed to have ideology. By this we mean that their goal is to maximize the welfare of their constituencies. (ii) The policy implemented after the election does not need to coincide with the one proposed by the winner. The policy implemented should be a compromise that considers the proposals made by the different parties. In the case of proportional representation this compromise is modeled as a convex combination of the proposed policies with weights proportional to the number of votes obtained by each party. We provide some existence theorems and compare the equilibrium in our model with the equilibrium that exists under some probabilistic models. It is also shown that proportional representation will create incentives for the parties to announce radical platforms. Received: 17 May 1994/Accepted: 5 March 1996     

Work histories and workers’ failure to satisfy pension contribution requirements: A comparison of Mexico and Uruguay

Comparing Mexico and Uruguay, this article examines the work history of workers and the challenges they face to satisfy the minimum contribution period for eligibility to receive a contributory old-age pension. Administrative data on work histories is used to formulate a survival model aimed at estimating hazard rates of entering and transitioning out of a given contribution status. This model is then used to perform a Monte Carlo simulation to forecast contribution histories. Results suggest that the hazard rate is negatively associated with the length of a worker’s spell in his or her current status and warn that, both in Mexico and Uruguay, a significant group of workers will find it difficult to gain entitlement to a contributory pension in old age. The manner in which each of these national systems has addressed the challenges associated with low contribution densities may explain the two countries’ very different coverage results.