Semiparametric multiple kernel estimators and model diagnostics for count regression functions

Abstract

This study concerns semiparametric approaches to estimate discrete multivariate count regression functions. The semiparametric approaches investigated consist of combining discrete multivariate nonparametric kernel and parametric estimations such that (i) a prior knowledge of the conditional distribution of model response may be incorporated and (ii) the bias of the traditional nonparametric kernel regression estimator of Nadaraya-Watson may be reduced. We are precisely interested in combination of the two estimations approaches with some asymptotic properties of the resulting estimators. Asymptotic normality results were showed for nonparametric correction terms of parametric start function of the estimators. The performance of discrete semiparametric multivariate kernel estimators studied is illustrated using simulations and real count data. In addition, diagnostic checks are performed to test the adequacy of the parametric start model to the true discrete regression model. Finally, using discrete semiparametric multivariate kernel estimators provides a bias reduction when the parametric multivariate regression model used as start regression function belongs to a neighborhood of the true regression model.     

Subjective Happiness of Lebanese College Youth in Lebanon: Factorial Structure and Invariance of the Arabic Subjective Happiness Scale

The present study evaluated the subjective happiness of Lebanese college youth using a multi-item rather than a single-item subjective happiness measure. An Arabic translation of the Subjective Happiness Scale (SHS) was administered to 273 Lebanese college youth from state- and private-run higher institutions of learning, as was the Arabic Adult Parental Acceptance-Rejection Questionnaire (Arabic PARQ). The reliability and validity of the Arabic SHS was tested in terms of factor analysis, internal consistency, and correlation with Arabic PARQ scores, as was the factorial invariance and relation of the scale across age, sex, marital status, birth order, and college campus. The Arabic SHS showed a reliable unitary structure similar to those found in other cultures, and factorial invariance across sex, marital status, birth order and college campus. While age, sex, marital status and birth order were independent of happiness scores, college students attending the private university reported greater happiness than those from the state-run academic setting. It was concluded that the Lebanese Arabic SHS is a reliable and valid measure of global subjective happiness, its factor structure is similar across other translated versions of the scale, and its scores are independent of age, sex, marital status and birth order.     

Does employee welfare affect corporate debt maturity?

This study examines the effect of employee well-being on the corporate debt maturity structure of U.S. firms. It hypothesizes that a firm's degree of commitment to employee welfare affects its debt maturity structure. Using a sample of 19,347 firm-year observations over the period 1991–2014, we find evidence that firms with higher employee welfare scores prefer long-term debt over short-term debt. This relationship is more pronounced for firms operating in human-capital-intensive industries and firms with lower labor union-membership rate. Our findings are robust to endogeneity concerns and insensitive to the use of alternative regression methods, variable measurements, and sample compositions. This paper provides novel evidence on the role of employment policies and practices in explaining variations in debt maturity.     

Qualité des produits alimentaires et marques de filières

Brands have recently cropped up in the distribution of fresh produce - a phenomenon closely linked to food and health crises in the past few years. Public authorities have been creating new control and monitoring procedures, tightening regulations on production and modifying regulations about official labels of quality. Meanwhile, retailers have been adopting new strategies for segmenting supply. How does this affect the supply of produce to consumers? How does it modify relations between producers and distributors? Under what conditions do these parties have an interest in complying? How do these segmentation strategies interact with the policies advocated by public officials and affect the raising of standards for a “minimum quality”? - Special issue on Agriculture and food.     

A multivariate non-parametric kernel estimator for global sensitivity analysis

The fact of estimating how a model output is influenced by the variations of inputs has become an important problematic in reliability and sensitivity analysis. This article is interested in estimating sensitivity indices useful to quantify the contribution of inputs to the variance of model output. A multivariate mixed kernel estimator is investigated since, until now, discrete and continuous inputs have been separately considered in kernel estimation of sensitivity indices. To illustrate the differences between the influence of mixed, discrete, and continuous inputs, analytical expressions of Sobol sensitivity indices are expressed in these three cases for the Ishigami test function. Besides, the performance of the mixed kernel estimator is illustrated through simulations in which the Bayesian procedure is applied for bandwidth parameter choice. An application is also realized on a real example. Finally, the use of an appropriate kernel estimator according to the type of inputs is found to be influential on the accuracy of sensitivity indices estimates.