Model selection criteria in beta regression with varying dispersion

We address the issue of model selection in beta regressions with varying dispersion. The model consists of two submodels, namely: for the mean and for the dispersion. Our focus is on the selection of the covariates for each submodel. Our Monte Carlo evidence reveals that the joint selection of covariates for the two submodels is not accurate in finite samples. We introduce two new model selection criteria that explicitly account for varying dispersion and propose a fast two step model selection scheme which is considerably more accurate and is computationally less costly than usual joint model selection. Monte Carlo evidence is presented and discussed. We also present the results of an empirical application.     

Tests for Structural Changes in Time Series of Counts

We propose methods for detecting structural changes in time series with discrete‐valued observations. The detector statistics come in familiar L2‐type formulations incorporating the empirical probability generating function. Special emphasis is given to the popular models of integer autoregression and Poisson autoregression. For both models, we study mainly structural changes due to a change in distribution, but we also comment for the classical problem of parameter change. The asymptotic properties of the proposed test statistics are studied under the null hypothesis as well as under alternatives. A Monte Carlo power study on bootstrap versions of the new methods is also included along with a real data example.     

A comparison of L-, LQ-, TL-moment and maximum likelihood high quantile estimates of the GPD and GEV distribution

In this article, L-moments, LQ-moments and TL-moments of the generalized Pareto and generalized extreme-value distributions are derived up to the fourth order. The first three L-, LQ- and TL-moments are used to obtain estimators of their parameters. Performing a simulation study, high-quantile estimates based on L-, LQ-, and TL-moments are compared to the maximum likelihood estimate with respect to their sample mean squared error. This consists of identifying an optimal combination of parameters α and p both considered in the range [0, 0.5] for estimating quantiles by LQ-moments. The results show L-moment and maximum likelihood methods outperform other methods.     

On fiducial generators

Fiducial inference has been gaining presence recently and it is the intention of the present article to look at the notion of fiducial generators; meaning procedures to simulate parameter values that in some sense correspond to simulations from some implicit fiducial distribution. It is well known that when the distribution has group structure, stemming from the natural pivotal associated, a fiducial may be obtained. It is in the non group distributions that there appears to be still room for finding a fiducial distribution. Recently some general procedures have been proposed for dealing with generalized fiducials, but these depend on certain choices for a structural equation or a fiducial equation, as in Hannig (2009 Hannig, J. (2009). On generalized fiducial inference. Stat. Sin. 19:491–544.[Web of Science ®] , [Google Scholar]) or Taraldsen and Lindqvist (2013 Taraldsen, G., Lindqvist, B.H. (2013). Fiducial theory and optimal inference. Ann. Stat. 41(1):323–341.[Crossref], [Web of Science ®] , [Google Scholar]), respectively. A brief presentation is made of an earlier approach to fiducial inference for multivariate parameters, as in Brillinger (1962 Brillinger, D.R. (1962). Examples bearing on the definition of fiducial probability with a bibliography. Ann. Math. Stat. 33(4):1349–1355.[Crossref] , [Google Scholar]), and the implied fiducial generator introduced in Engen and Lillegård (1997 Engen, S., Lillegård, M. (1997). Stochastic simulation conditioned on sufficient statistics. Biometrika 84(1):235–240.[Crossref], [Web of Science ®] , [Google Scholar]), trying to connect them. Three interesting non group distributions are seen; two of them, the truncated exponential and the two-parameter gamma, already reported in literature. A third non group distribution is analyzed; the inverse Gaussian, connecting the fiducial that results following Brillinger (1962 Brillinger, D.R. (1962). Examples bearing on the definition of fiducial probability with a bibliography. Ann. Math. Stat. 33(4):1349–1355.[Crossref] , [Google Scholar]), with a result pertaining confidence limits for the shape parameter in Hsieh (1990 Hsieh, H.K. (1990). Inferences on the coefficient of variation of an inverse-Gaussian distribution. Commun. Stat. - Theory Methods 19(5):1589–1605.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). In the three cases, comparisons are made with the Bayesian posteriors that have been known to be close numerically. Some discussion is made on the issue of singularities of the fiducial density and its connection with densities that do not integrate to unity. As to the case of discrete observables, some comments are made for the Bernoulli distribution, only.     

Discussing Global Issues Through Contemporary Art

Contemporary global issues can be examined through the lens of modern photographic art. In an effort to prepare global-ready graduates, this article explores the pressing problems of environmental degradation, urbanization, and homelessness through the work of three contemporary artists. Illustrative works, suggested approaches, and curriculum resources are provided.     

Corruption and the ‘Paradox of Redistribution’

The existing literature on the determinants of income redistribution has identified a ‘paradox’. Namely, that countries with a high degree of market income inequality redistribute little, which is in disagreement with the median voter theorem. In a first step, this paper outlines several mechanisms that explain why government corruption might be partially responsible for this ‘paradox’. In a second step, different corruption perception indices and an instrumental variable approach are used to provide empirical evidence that indicates a significant negative impact of corruption on redistribution levels for a sample of 148 developing and developed countries. This finding suggests that, next to political and need factors, government corruption explains to some extent the ‘paradox of redistribution’. This is especially true for many developing countries, given that they typically have relatively high degrees of corruption and low levels of redistribution.     

What is Happening with Quality of Life Among the Oldest People in Southern European Countries? An Empirical Approach Based on the SHARE Data

Population aging in developed countries has created new challenges to improve the well-being of individuals at different age cohorts. This issue is especially significant for Southern European countries, were aging societies have worse health and less socio-economic resources. The aim of this study is to contribute to this body of literature and to estimate the effect of aging on quality of life of oldest people. This paper uses the latest available data (6th wave) from the Survey on Health, Ageing and Retirement in Europe (SHARE). Specifically, robust ordinary least squares and multilevel regressions are employed to analyse the effects of socioeconomic, health, and community factors on quality of life among the oldest population for Southern European countries. Our findings confirm the significance of several factors on life satisfaction among the oldest population in this group of countries. Moreover, we show that the determinants which are correlated with quality of life include predisposing, health, geographic area and social isolation factors.     

Relationship between duration of second stage of labour and postpartum anaemia

Aim

To assess the relationship between the duration of the second stage of labour and postpartum anaemia during vaginal birth.

“Unnatural Fornication” Cases Under State-Socialism: A Hungarian–Slovenian Comparative Social-Historical Approach

This comparative social-historical study examines different versions of state-socialist body politics manifested in Hungary and Slovenia mainly during the 1950s by using archive material of “unnatural fornication” court cases. By analyzing the available Hungarian “természet elleni fajtalanság” and Slovenian “nenaravno ob?evanje” court cases, we can shed light on how the defendants were treated by the police and the judiciary. On the basis of these archive data that have never been examined before from these angles, we can construct an at least partial picture of the practices and consequences of state surveillance of same-sex-attracted men during state-socialism. The article explores the functioning of state-socialist social control mechanisms directed at nonnormative sexualities that had long-lasting consequences on the social representation of homosexuality in both countries.