Detecting serial dependencies with the reproducibility probability autodependogram

The autodependogram is a graphical device recently proposed in the literature to analyze autodependencies. This paper proposes a normalization of this diagram taking into consideration the concept of reproducibility probability (RP). The result is a novel tool, named RP-autodependogram, which permits to study the strength and the stability of the evidence about the presence of lag-dependence. A simulation study on well-established time-series models is carried out to investigate the behavior of the RP-autodependogram also in comparison with other diagrams studying autodependencies. An application to financial data is finally considered to appreciate its usefulness in the identification of parametric/nonparametric models.     

A New Approach to Rank Several Multivariate Normal Populations with Application to Life Cycle Assessment

The need to establish the relative superiority of each treatment when compared to all the others, i.e., ordering the underlying populations according to some pre-specified criteria, often occurs in many applied research studies and technical/business problems. When populations are multivariate in nature, the problem may become quite difficult to deal with especially in case of small sample sizes or unreplicated designs. The purpose of this work is to propose a new approach for the problem of ranking several multivariate normal populations. It will be theoretically argued and numerically proved that our method controls the risk of false ranking classification under the hypothesis of population homogeneity while under the nonhomogeneity alternatives we expect that the true rank can be estimated with satisfactory accuracy, especially for the “best” populations. Our simulation study proved also that the method is robust in the case of moderate deviations from multivariate normality. Finally, an application to a real case study in the field of life cycle assessment is proposed to highlight the practical relevance of the proposed methodology.     

Sustainable storage assignment and dwell-point policies for automated storage and retrieval systems

Picking time reduction has been the traditional perspective for warehouse optimisation. When sustainability is considered, optimisation of warehouse operations should be read in terms of energy efficiency other than response time. Each location in the rack of an automated storage and retrieval system is associated with the value of energy consumed by the crane to reach it. Since picking performance strictly depends on storage location assignments, the time-based full turnover strategy is compared to the energy-based one. Three models of energy consumption are considered for traditional and new-generation cranes. Assignments are then compared in terms of dedicated zone shapes, time and energy performances within a given time horizon. Different shapes of the rack and product ABC curves are analysed. Dwell-point policies are also analysed from the new sustainable perspective, adding energy-saving performance to the traditional picking time reduction.     

Estimating the Effect of Perceived Risk of Crime on Social Trust in the Presence of Endogeneity Bias

This study aims to estimate the effect of perceived risk of crime on the social trust probability for Italian men and women, accounting for both observed and unobserved confounding. We use microdata collected by the Italian National Statistical Office for the year 2010 during a multi-scope survey of Italian households. The relationship under investigation is estimated after controlling for observed confounding by using a propensity score weighting approach. To control for both observed and unobserved confounding (better known as endogeneity), a semiparametric recursive bivariate probit approach is ultimately employed instead. Our findings show that the perceived risk of crime has a significant negative effect on the social trust probability regardless of gender and that endogeneity seems to be present for both genders. The paper represents the first such application in which the effect of interest is estimated accounting for the presence of endogeneity.     

Civil Society Networks: Options for Network Design

Civil society networks are critical actors in international development and social change, even as they are organizationally complex and challenging to design and manage. Network forms of organization may be “neither markets nor hierarchies,” but there is little shared understanding globally about the options that exist for designing interorganizational network structures or the conditions under which different options may be selected. This empirical study of thirty networks across eleven sectors and five global regions contributes a new conceptual framework for categorizing different types of network structures based on the level of interdependence among network members. Findings reveal three distinct network design options, indicate patterns of network development, and suggest several conditions that may influence the design of civil society networks.     

Detecting Unobserved Heterogeneity in the Relationship Between Subjective Well-Being and Satisfaction in Various Domains of Life Using the REBUS-PLS Path Modelling Approach: A Case Study

In this article, we propose a model to estimate the direct and indirect effects of the relationship between subjective well-being and satisfaction in various domains of life using a partial least squares path modelling approach in a structural equation model framework. A drawback of these models is that they assume homogeneous behaviour over the observed set of units. To address this issue, Trinchera (Ph.D. thesis, University of Naples, 2007) and Esposito Vinzi et al. (Appl Stoch Models Bus Ind 28:439–458, 2008) proposed an algorithm, called the response-based unit segmentation in partial least squares (REBUS-PLS) path modelling, to detect sources of heterogeneity in both measurement and structural models. The REBUS-PLS allows researchers to identify classes of units with similar behaviours (with respect to the postulated model) and to estimate one model for each identified class (so-called ‘local models’). Applying the REBUS-PLS algorithm to our case study, we detected three main classes of units with similar behaviours and estimated three local models. We found, for example, that in the estimated model for the entire sample, the relationship between satisfaction with family and social life and subjective well-being is statistically significant. However, this result was not confirmed in all of the estimated local models.     

Fertility-related pensions and cyclical instability

In this paper, we study a general equilibrium model with overlapping generations, endogenous fertility and public pensions. By assuming Cobb–Douglas technology and logarithmic preferences, we show that the introduction of a fertility-related component in the pay-as-you-go pension scheme may destabilise the long-term equilibrium and cause endogenous fluctuations when individuals have static expectations. The possibility of cyclical instability increases (resp. reduces) when both the subjective discount factor and relative weight of individual fertility in pay-as-you-go pensions (resp. the parents’ taste for children) increase(s). Interestingly, when public pensions are contingent on the individual number of children, the financing of small-sized benefits may cause the occurrence of a flip bifurcation, two-period cycles and cycles of a higher order. In addition, we show through numerical simulations that these results hold in a more general setting with a constant inter-temporal elasticity of substitution utility function and a constant elasticity of substitution production function. Our findings identify a possible novel factor responsible for persistent deterministic fluctuations in a context of overlapping generations, while also representing a policy warning regarding the destabilising effects of fertility-related pension reforms, which are currently high in both the theoretical debate and the political agendas of several developed countries.