Testing for additivity and joint effects in multivariate nonparametric regression using Fourier and wavelet methods

We consider the problem of testing for additivity and joint effects in multivariate nonparametric regression when the data are modelled as observations of an unknown response function observed on a d-dimensional (d 2) lattice and contaminated with additive Gaussian noise. We propose tests for additivity and joint effects, appropriate for both homogeneous and inhomogeneous response functions, using the particular structure of the data expanded in tensor product Fourier or wavelet bases studied recently by Amato and Antoniadis (2001) and Amato, Antoniadis and De Feis (2002). The corresponding tests are constructed by applying the adaptive Neyman truncation and wavelet thresholding procedures of Fan (1996), for testing a high-dimensional Gaussian mean, to the resulting empirical Fourier and wavelet coefficients. As a consequence, asymptotic normality of the proposed test statistics under the null hypothesis and lower bounds of the corresponding powers under a specific alternative are derived. We use several simulated examples to illustrate the performance of the proposed tests, and we make comparisons with other tests available in the literature.     

Mothers,fathers and children after divorce: The role of institutions

In recent years the increase in the divorce rate in many advanced countries and the predominance of female-headed families among the poor has generated much interest in the relationship between divorce and the welfare of mothers and children. In this paper I will review a small body of economic literature which has been recently developed in order to analyze the economic consequence of divorce on the welfare of fathers, mothers and children under alternative behavioral assumptions. Important economic and econometric issues arise from an analysis of welfare in non intact households as compared with intact households. In particular the focus is on the role that institutions play in post-divorce arrangements and important implications concerning policies for child support, custody, and visitation.Presidential Address of the Annual Congress of ESPE2000 held on June 15, 2000 in Bonn. I would like to thank Christopher Flinn, Rocio Ribero, Maristella Botticini and two anonymous referees for their helpful comments. Responsible editor: Alessandro Cigno.     

Testing appearance of linear trend

A test for the detection of a gradual change in simple linear regression is studied. Asymptotic distribution of the “maximum type” statistic is derived. Asymptotic critical values are compared with critical values obtained by simulations. The problem was motivated by the effort of meteorologists to discover a change in meteorological measurements.     

Applying multivariate techniques to high-dimensional temporally correlated fMRI data

In first-level analyses of functional magnetic resonance imaging data, adjustments for temporal correlation as a Satterthwaite approximation or a prewhitening method are usually implemented in the univariate model to keep the nominal test level. In doing so, the temporal correlation structure of the data is estimated, assuming an autoregressive process of order one.We show that this is applicable in multivariate approaches too - more precisely in the so-called stabilized multivariate test statistics. Furthermore, we propose a block-wise permutation method including a random shift that renders an approximation of the temporal correlation structure unnecessary but also approximately keeps the nominal test level in spite of the dependence of sample elements.Although the intentions are different, a comparison of the multivariate methods with the multiple ones shows that the global approach may achieve advantages if applied to suitable regions of interest. This is illustrated using an example from fMRI studies.     

CSR committees on boards: the impact of the external country level factors

Journal of Management and Governance - This article explores the spread of corporate social responsibility (CSR) committees in the European countries, examining whether and what country level...     

Making sources of energy: the case of coal (1900–1936)

Recent contributions to a sociological analysis of energy and society focus mostly on its political, economic and technological organization. Yet contrary to other parts of nature, little social scientific attention has been paid to how politics, economics and technology have come to produce and stabilize the concept of energy in the first place and how different natural materials were transformed into “sources of energy.” Drawing from insights of the sociology of comparison, quantification and commensuration, “energy” in this paper is conceived as a “statistical object,” around which a public discourse develops in which comparisons between resources are drawn. Since the beginning of the twentieth century, this discourse has been more and more stabilized by the regular, public production and ever tighter net of elements of comparison, the creation of a highly abstract, potentially quantified point of comparison, and the definition of various criteria tying the compared entities together with more general models and narratives. This theoretical framework is put into practice by an explorative analysis of coal classification in the first quarter of the twentieth century. In this empirical analysis, three fields are identified where coals were “made the same”: engineering, economics and resource statistics. It is shown that the “calorific value” plays an important role for classification in all three fields and, furthermore, constitutes a measure that links coal to other fuels.     

Employment Trajectories Beyond Retirement

Within the political and academic debate on working longer, post-retirement employment is discussed as an alternative to maintain older workers in the labor market. Our article enhances this discussion by studying determinants of transitions into post-retirement jobs within differing work environments of birth cohorts 1940–1942. We estimate proportional subhazard models accounting for competing risks using unique German social security data linked to pension accounts. Our findings suggest that individuals’ preferences to take up post-retirement jobs are not mutually exclusive. Our study provides evidence that taking up post-retirement jobs is related to seeking financial security, continuity, and work ability, suggesting that public policy has to develop target-oriented support through a public policy mix of different measures aligned to the different peer groups in the labor market.     

How Leaders Affect Followers’ Work Engagement and Performance: Integrating Leader−Member Exchange and Crossover Theory

Drawing on leader?member exchange and crossover theory, this study examines how leaders’ work engagement can spread to followers, highlighting the role of leader?member exchange as an underlying explanatory process. Specifically, we investigate if leaders who are highly engaged in their work have better relationships with their followers, which in turn can explain elevated employee engagement. For this purpose, we surveyed 511 employees nested in 88 teams and their team leaders in a large service organization. Employees and supervisors provided data in this multi‐source design. Furthermore, we asked the employees to report their annual performance assessment. We tested our model using multilevel path analyses in Mplus. As hypothesized, leaders’ work engagement enhanced leader?member exchange quality, which in turn boosted employee engagement (mediation model). Moreover, employee engagement was positively linked to performance and negatively linked to turnover intentions. As such, our multilevel field study connects the dots between work engagement research and the leadership literature. We identify leaders’ work engagement as a key to positive leader?follower relationships and a means for promoting employee engagement and performance. Promoting work engagement at the managerial level may be a fruitful starting point for fostering an organizational culture of engagement.     

First Exits from the Swedish Labor Market Due to Disability

Nowadays, with an increasingly aging population, an increasing proportion of the population on disability benefits, and an implicitly lower level of economic output and foregone tax revenue, disability has become a major public policy issue in many countries. Estimating both single risk and competing risks models on a Swedish longitudinal database, this study analyzes the risk of exit from the labor market due to disability at a certain age, conditional on having remained in the labor force until that age. The explanatory variables did not have identical coefficients across destination types. For example, the estimated single risk model shows that a higher level of education decreased the hazard of exiting the labor market with a disability pension, while the estimated competing risks model suggests that a higher level of education increased the hazard of exiting with a partial disability pension, but it decreased the hazard of exiting with a full disability pension.

Facts and Theories of the Italian Labour Market (1970-1985): A Time Series Analysis of Wages,Employment and Prices

ABSTRACT: ln this paper an attempt is made to determine whether observed patterns of intertemporal variability in a number of Italian labour market characteristics are consistent with the predictions forthcoming from three prominent models of aggregate labour market behaviour. The behavioral models included in the analysis are: a) intertemporal substitution labour supply, b) staggered wage contracts, and c) intertemporal labour demand with adjustment costs. The empirical results provide relatively more support for the validity of the adjustment cost model.