Divorce and the business cycle: a cross-country analysis

In this paper, we examine the role of the business cycle in divorce. To do so, we use a panel of 29 European countries covering the period from 1991 to 2012. We find the unemployment rate negatively affects the divorce rate, pointing to a pro-cyclical evolution of the divorce rate, even after controlling for socio-economic variables and unobservable characteristics that can vary by country, and/or over time. Results indicate that a one-percentage-point increase in the unemployment rate involves almost 0.025 fewer divorces per thousand inhabitants. The impact is small, representing around 1.2 % of the average divorce rate in Europe during the period considered. Supplementary analysis, developed to explore a possible non-linear pattern, confirms a negative relationship between unemployment and divorce in European countries, with the inverse relationship being more pronounced in those countries with higher divorce rates.     

A Wald-type test statistic based on robust modified median estimator in logistic regression models

In this paper a new robust estimator, modified median estimator, is introduced and studied for the logistic regression model. This estimator is based on the median estimator considered in Hobza et al. [Robust median estimator in logistic regression. J Stat Plan Inference. 2008;138:3822–3840]. Its asymptotic distribution is obtained. Using the modified median estimator, we also consider a Wald-type test statistic for testing linear hypotheses in the logistic regression model and we obtain its asymptotic distribution under the assumption of random regressors. An extensive simulation study is presented in order to analyse the efficiency as well as the robustness of the modified median estimator and Wald-type test based on it.     

Empirical characteristic function tests for GARCH innovation distribution using multipliers

Goodness-of-fit tests for the innovation distribution in GARCH models based on measuring deviations between the empirical characteristic function of the residuals and the characteristic function under the null hypothesis have been proposed in the literature. The asymptotic distributions of these test statistics depend on unknown quantities, so their null distributions are usually estimated through parametric bootstrap (PB). Although easy to implement, the PB can become very computationally expensive for large sample sizes, which is typically the case in applications of these models. This work proposes to approximate the null distribution through a weighted bootstrap. The procedure is studied both theoretically and numerically. Its asymptotic properties are similar to those of the PB, but, from a computational point of view, it is more efficient.     

Bivariate degradation modelling with marginal heterogeneous stochastic processes

In this paper, we consider that the degradation of two performance characteristics of a product can be modelled by stochastic processes and jointly by copula functions, but different stochastic processes govern the behaviour of each performance characteristic (PC) degradation. Different heterogeneous and homogeneous models are presented considering copula functions and different combinations of the most used stochastic processes in degradation analysis as marginal distributions. This is an important aspect to consider because the behaviour of the degradation of each PC may be different in its nature. As the joint distributions of the proposed models result in complex distributions, the estimation of the parameters of interest is performed via MCMC. A simulation study is performed to compare heterogeneous and homogeneous models. In addition, the proposed models are implemented to crack propagation data of two terminals of an electronic device, and some insights are provided about the product reliability under heterogeneous models.     

Confidence band for percentile line in multiple linear regression

We deal with the problem of estimating constructing a confidence band for the 100γth percentile line in the multiple linear regression model with independent identically normally distributed errors. A method for computing the exact Scheffé type confidence band over a limited space of the particular covariates region is suggested. A confidence band depends on an estimator of the percentile line. The confidence bands based on the different estimators of the percentile line are compared with respect to the average bandwidth.     

Darling-Erdös-type test for change detection in parameters and variance for stationary VAR models

The aim of this article is the construction of the test statistic for the detection of changes in vector autoregressive (AR) models where both AR parameters and the variance matrix of the error term are the subjects of a change. The approximating distribution of the proposed statistic is the Gumbel distribution. The proof stands on the approximation of weakly dependent random vectors by independent ones and by application of Horváth’s extension of Darling-Erdös extremal result for random vectors, see Darling and Erdös (1956) Darling, D.A., Erdös, P. (1956). A limit theorem for the maximum of normalized sums of independent random variables. Duke Math. J. 23:143–155.[Crossref], [Web of Science ®] , [Google Scholar] and Horváth (1993) Horváth, L. (1993). The maximum likelihood method for testing changes in the parameters of normal observations. Ann. Stat. 21(2):671–680.[Crossref], [Web of Science ®] , [Google Scholar]. The test statistic is a modification of the likelihood ratio.     

Organisation Workshop. Beyond the Workplace: Large Groups,Activity and the Shared Object

Organisation Workshop stands for a body of practice derived from the pioneering work that Clodomir de Morais did with the Brasilian Peasant Leagues starting in the early 1960s and shown to be relevant today in situations of high unemployment. Two essential ingredients are a large group and a common resource pool. The Organisation Workshop method is illuminated by Leontiev’s “objectivised activity” concept, as well as important insights from 3 generations of activity theory (CHAT). Moraisean thought and practice are shown to open up new avenues to community development and to break new ground in the social psychology of the large group.     

Correction to: Analysis of environmental flow requirements for macroinvertebrates in a creek affected by urban drainage (Prague metropolitan area,Czech Republic)

Urban Ecosystems - The original version of this article unfortunately contained errors. The given name and family name of all the authors were interchanged. Dana, Jana and Tomá? are given...     

PI3K pathway and Bcl-2 family. Clinicopathological features in prostate cancer

The phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathways and Bcl-2 family play a central role in prostate cancer (PC). The aim was to determine influence in the biochemical progression in PC. To evaluate the association between clinic pathological and immunohistochemical variables, Spearman’s test was performed. Log-rank test and Kaplan–Meier curves were used for survival comparisons. To explore the correlation of the studied immunohistochemical parameters and the established prognostic variables with biochemical progression, univariate and multivariate Cox proportional Hazard regression analyses were performed. Spearman analysis showed correlation between stroma expression and tumor expression of PI3K with biochemical progression (p?=?.009, p?=?.004), respectively, and tumor immunohistochemical score with biochemical progression (p?=?.051). In the multivariate Cox regression model, only PI3K was retained as independent predictors of biochemical progression. In stroma expression, PI3K is (HR 0.172, 95% CI 0.065–0.452, p?=?.000); tumor expression, PI3K is (HR 0.087, 95% CI 0.026–0.293, p?=?.000), and tumor immunohistochemical score (HR 0.382, 95% CI 0.209–0.697 p?=?.002). Our results suggest a role for prostatic expression of PI3K was prognostic markers for PC. PI3K/AKT/mTOR and Bcl-2 family are becoming an important therapeutic target and predictive biomarkers of onset and progression of PC.