An optimization approach applied to the optimal stratification problem

A new optimization algorithm is presented to solve the stratification problem. Assuming the number L of strata and the total sample size n are fixed, we obtain strata boundaries by using an objective function associated with the variance. In this problem, strata boundaries must be determined so that the elements in each stratum are more homogeneous among themselves. To produce more homogeneous strata, this paper proposes a new algorithm that uses the Greedy Randomized Adaptive Search Procedure (GRASP) methodology. Computational results are presented for a set of problems, with the application of the new algorithm and some algorithms from literature.     

Simulation-based model comparison methodology with application to road accident models

This article assumes the goal of proposing a simulation-based theoretical model comparison methodology with application to two time series road accident models. The model comparison exercise helps to quantify the main differences and similarities between the two models and comprises of three main stages: (1) simulation of time series through a true model with predefined properties; (2) estimation of the alternative model using the simulated data; (3) sensitivity analysis to quantify the effect of changes in the true model parameters on alternative model parameter estimates through analysis of variance, ANOVA. The proposed methodology is applied to two time series road accident models: UCM (unobserved components model) and DRAG (Demand for Road Use, Accidents and their Severity). Assuming that the real data-generating process is the UCM, new datasets approximating the road accident data are generated, and DRAG models are estimated using the simulated data. Since these two methodologies are usually assumed to be equivalent, in a sense that both models accurately capture the true effects of the regressors, we are specifically addressing the modeling of the stochastic trend, through the alternative model. Stochastic trend is the time-varying component and is one of the crucial factors in time series road accident data. Theoretically, it can be easily modeled through UCM, given its modeling properties. However, properly capturing the effect of a non-stationary component such as stochastic trend in a stationary explanatory model such as DRAG is challenging. After obtaining the parameter estimates of the alternative model (DRAG), the estimates of both true and alternative models are compared and the differences are quantified through experimental design and ANOVA techniques. It is observed that the effects of the explanatory variables used in the UCM simulation are only partially captured by the respective DRAG coefficients. This a priori, could be due to multicollinearity but the results of both simulation of UCM data and estimating of DRAG models reveal that there is no significant static correlation among regressors. Moreover, in fact, using ANOVA, it is determined that this regression coefficient estimation bias is caused by the presence of the stochastic trend present in the simulated data. Thus, the results of the methodological development suggest that the stochastic component present in the data should be treated accordingly through a preliminary, exploratory data analysis.     

Intergenerational mobility of housework time in the United Kingdom

This paper analyzes the relationship between parents’ time devoted to housework and the time devoted to housework by their children. Using data from the Multinational Time Use Study for the UK, we find positive intergenerational correlations in housework for both parents, indicating that the more time parents devote to housework, the more time their children will devote to housework. Using data from the British Household Panel Survey, we find that a higher father–mother housework ratio is positively related to a higher child–mother housework ratio, even after allowing for individual fixed-effects. In order to address the potential exacerbation of errors-in-variables arising from the fixed-effects specification, we instrument the father–mother ratio of housework using father’s and mother’s lagged weekly working hours. The Instrumental-Variable estimates fully support the fixed-effects estimates, and suggest that the latter should be regarded as a lower bound. We also present evidence of the link between housework during adolescence and during adulthood, which may indicate that housework time during adulthood depends on the housework time during childhood, which may also be affected by parents’ housework time. Our results contribute to the field of the intergenerational mobility of behaviors.     

Socioemotional wealth’s implications in the calculus of the minimum rate of return required by family businesses’ owners

This paper demonstrates that the minimum rate of return (k _e ) required by family business shareholders is inversely related to the emotional endowment presented in these firms. After reviewing the socioemotional wealth (SEW) literature, we find empirical support to justify that different SEW dimensions influence k _e . Findings from a population of 207 family firms show that the identification of family members with the firm and the renewal of family bonds with the firm through dynastic succession have consistently negative impacts on k _e , while family control and influence have significantly positive impacts on k _e .     

Adolescent and parent alliances with therapists in Brief Strategic Family Therapy with drug-using Hispanic adolescents

This study examined the relationship between alliance and retention in family therapy. Alliance was examined at the individual (parent, adolescent) and family level (within-family differences) for families that either dropped out or completed family therapy. Participants were 31 Hispanic adolescents and their family members who received brief strategic family therapy for the treatment of adolescent drug use. Videotapes of first sessions were rated to identify parent and adolescent alliances with the therapist. Results demonstrated that Completer cases had significantly higher levels of alliance across all family members than Dropout cases, and Dropout cases had significantly higher unbalanced alliances than Completer cases. Clinical implications are discussed.     

Emancipation and Self-determination of People with Learning Disabilities and Down-sizing Institutional Care

In Arduin, an organisation for services to people with learning disabilities in the Netherlands, the emancipation and self-determination of people with learning disabilities has been positively adopted as fundamental in order to secure the best possible quality of life of the clients. The client is being encouraged in several ways in a development from a position of dependence towards self-determination. The services provided by the organisation had to be adjusted accordingly and are also going through a transition from 'providing a total care service' towards 'offering the support that the client desires'. In this article the background and developments in perception are being outlined, and those dimensions in quality of life are elaborated that are seen as most essential in the innovation: inclusion, self-determination and personal development. The choices that were made as a consequence in Arduin and most fundamental the choice to dismantle the institution are described.     

Nonparametric estimation of a regression function from backward recurrence times in a cross-sectional sampling

This study considers the nonparametric estimation of a regression function when the response variable is the waiting time between two consecutive events of a stationary renewal process, and where this variable is not completely observed. In these circumstances, our data are the recurrence times from the occurrence of the last event up to a pre-established time, along with the corresponding values of a certain set of covariates. Estimation of the error density function and some of its characteristics are also considered. For the proposed estimators, we first analyze their asymptotic behavior and, thereafter, carry out a simulation study to highlight their behavior in finite samples. Finally, we apply this methodology to an illustrative example with biomedical data.     

Youth talking about news and civic daily life

This paper considers how young people talking about news and politics in their family and peer contexts influences their civic life. The research involved 35 Portuguese youngsters from diverse social, economic and cultural backgrounds that were interviewed in 2010, in Portugal, at the onset of the Eurozone crisis. Based on talking and news-mediated contexts and habits, we identified three different profiles: Limitations to empowerment; Civic capital and self-empowerment; and socioeconomic conditions and empowerment. These profiles show how family and peer talking play a central role in strengthening and making a habitus of being an active citizen, even in contexts with limited cultural, economic and social conditions.