Tree-structured generalized autoregressive conditional heteroscedastic models

We propose a new generalized autoregressive conditional heteroscedastic (GARCH) model with tree-structured multiple thresholds for the estimation of volatility in financial time series. The approach relies on the idea of a binary tree where every terminal node parameterizes a (local) GARCH model for a partition cell of the predictor space. The fitting of such trees is constructed within the likelihood framework for non-Gaussian observations: it is very different from the well-known regression tree procedure which is based on residual sums of squares. Our strategy includes the classical GARCH model as a special case and allows us to increase model complexity in a systematic and flexible way. We derive a consistency result and conclude from simulation and real data analysis that the new method has better predictive potential than other approaches.     

Discussion of paper 'explanations of the fertility crisis in modern societies: a search for commonalities', Population Studies 57(3): 241-263, by John Caldwell and Thomas Schindlmayr

The contributors to this discussion were invited to submit comments, each from a different standpoint, on the paper by John Caldwell and Thomas Schindlmayr that appeared in the preceding issue of the journal. The invitation was issued with the approval of these authors, and the journal is grateful to them for allowing their paper to be used to generate debate on the issues they had raised. The discussion is followed by the authors' response to it.     

Agroenvironmental policies in Slovenia: a multivariate and multicriteria approach

This study was conducted when Slovenia was still harmonising its environmental legislation with the acquis communautaire; a process that today has been fully completed. Moreover, Slovenian state intervention in favour of rural development aims to stimulate both the conservation of natural resources and the growth of the primary sector. In this paper we suggest that these issues could be addressed through the application of multivariate statistics and multicriteria decision methods. By using these methods it would be possible to achieve a better understanding of the importance of territorial structure and socioeconomic characteristics. Our aim is to identify institutional agricultural measures that are able to protect the environment.     

Nonlinear models for ground-level ozone forecasting

One of the main concerns in air pollution is excessive tropospheric ozone concentration. The aim of this work is to develop statistical models giving shortterm forecasts of future ground-level ozone concentrations. Since there are few physical insights about the dynamic relationship between ozone, precursor emissions and/or meteorological factors, a nonparametric and nonlinear approach seems promising in order to specify the forecast models. First, we apply four nonparametric procedures to forecast daily maximum 1-hour and maximum 8-hour averages of ozone concentrations in an urban area. Then, in order to improve the forecast performances, we combine the time series of the forecasts. This idea seems to give encouraging results. This work was supported by a MURST grant. The authors would like to thank two anonymous referees for their helpful comments.     

The Collaborations-Relations Between Western (Secular) Law and Religious<Emphasis Type="Italic"> Nomoi</Emphasis> Groups in Today’s Multicultural Context: The Cases of France and Canada

In the last decade, under the pressing processes of immigration and globalisation, many Western constitutional democracies have moved from a number of religions sharing a common culture to today’s age of diversity. What current democracies are facing is the lack of overlapping consensus over basic constitutional “values”. The nature, scope and force of such values are likely to be affected by competing and, sometimes, contested fundamental reasons and worldviews. From here stems the dilemma between “unity” and “diversity”. This essay starts with a broad consideration on the principle of religious freedom, strictly related to the separation as well as collaboration between secular States and Churches; then the author analyses two case-studies (France and Canada), pointing out some specific legal approaches. In particular he focuses the analyses over the French “droit commun” and the Canadian arbitral tribunals that, especially in family law, allow disputes to be arbitrated using religious jurisdictions.     

Why still marry? The role of feelings in the persistence of marriage as an institution1

Despite cohabitation becoming increasingly equivalent to marriage in some of the most ‘advanced’ Western European societies, the vast majority of people still marry. Why so? Existing theories, mostly based on various approaches tied to cognitive decision‐making, do not provide a sufficient explanation of the persistence of marriage. In this article, we argue that feelings attached to marriage, i.e. the affective evaluation of those involved in a partner relationship concerning marriage as opposed to cohabitation, explain the persistent importance of marriage as an institution. We argue that socialization, biological and social‐structural factors affect these affective evaluations. We provide a test of our hypotheses using a longitudinal study of young adults in the Netherlands. The results of our analyses are consistent with a central role of feelings in the decision to marry, as well as with a role for key moderating factors such as gender.     

Response: Avuncularity and Kin Selection in Homosexuals: A Problematic Test or a Problematic Hypothesis?

Here we respond to Vasey et al.'s critical comments regarding our article, “Societal norms rather than sexual orientation influence kin altruism and avuncularity in tribal Urak-Lawoi, Italian, and Spanish adult males” (Camperio Ciani, Battaglia, &; Liotta, 2015 Camperio Ciani, A., Battaglia, U., &; Liotta, M. (2015). Societal norms rather than sexual orientation influence kin altruism and avuncularity in tribal Urak-Lawoi, Italian, and Spanish adult males. Journal of Sex Research. Advance online publication. doi:10.1080/00224499.2014.993748[Taylor &; Francis Online] , [Google Scholar], JSR doi:10.1080/00224499.2014.993748). The first regards the selection of the Urak-Lawoi population of Ko Lipeh, which is considered too modern and touristic to be adequate to test the kin selection and avuncular hypothesis for homosexuality. We provide historical evidence of the contrary, and show that the population at the inception of our 10 years research was indeed primitive and tribal, and probands actually grew and lived in such a society. Only a few years after the 2004 tsunami, the island was developed and invaded by mass tourism. The second comment regarded the statistical analysis and interpretation of data. We show that we consistently and conservatively considered the effects of all confounding variables, both with comparative tests, and by a series of multivariate regression analyses. This was the orthodox procedure approved by all other reviewers. In conclusion, even addressing these comments, we maintain that the kin selection and avuncularity hypothesis for homosexuality is not supported by empirical data even in this primitive and tribal society.     

Fitting logistic multilevel models with crossed random effects via Bayesian Integrated Nested Laplace Approximations: a simulation study

Fitting cross-classified multilevel models with binary response is challenging. In this setting a promising method is Bayesian inference through Integrated Nested Laplace Approximations (INLA), which performs well in several latent variable models. We devise a systematic simulation study to assess the performance of INLA with cross-classified binary data under different scenarios defined by the magnitude of the variances of the random effects, the number of observations, the number of clusters, and the degree of cross-classification. In the simulations INLA is systematically compared with the popular method of Maximum Likelihood via Laplace Approximation. By an application to the classical salamander mating data, we compare INLA with the best performing methods. Given the computational speed and the generally good performance, INLA turns out to be a valuable method for fitting logistic cross-classified models.     

Integrating macro- and micro-level approaches in the explanation of population change

Demographers study population change across time and place, and traditionally they place a strong emphasis on a long-range view of population change. This paper builds on current reflections on how to structure the study of population change and proposes a two-stage perspective. The first stage, discovery, focuses on the production of novel evidence at the population level. The second stage, explanation, develops accounts of demographic change and tests how the action and interaction of individuals generate what is discovered in the first stage. This explanatory stage also provides the foundation for the prediction of demographic change. The transformation of micro-level actions and interactions into macro-level population outcomes is identified as a key challenge for the second stage. Specific instances of research are discussed.