Clustering via nonparametric density estimation

Although Hartigan (1975) had already put forward the idea of connecting identification of subpopulations with regions with high density of the underlying probability distribution, the actual development of methods for cluster analysis has largely shifted towards other directions, for computational convenience. Current computational resources allow us to reconsider this formulation and to develop clustering techniques directly in order to identify local modes of the density. Given a set of observations, a nonparametric estimate of the underlying density function is constructed, and subsets of points with high density are formed through suitable manipulation of the associated Delaunay triangulation. The method is illustrated with some numerical examples.     

Social Politics and Policy in an Era of Globalization: Critical Reflections

This paper critically examines the ways in which social policy is said to be affected by globalization. The prevailing approach has been framed in terms of the impact of "external" economic forces on national welfare states. Globalization is said to undermine the economic and political conditions on which welfare states were built, erode national policy autonomy and force the marketization and residualization of welfare states. These predictions are found wanting on the grounds that they share many of the assumptions, and therefore also the faults, of "strong" globalization theory. A more nuanced account of the way in which social politics and social policy are affected by globalization is needed and a global governance perspective is outlined. This, it is argued, better captures the political and institutional environment in which social policy is formulated and implemented. It also recognizes the importance of "local" factors and their interaction with global ones in shaping political responses, including social policy, to globalization. The discussion highlights the enduring power of "local" forces—those which are at the level of and internal to states—and of politics and ideology in shaping the process of globalization and ultimately its implications for welfare states and social policies.     

Flattening the learning curve of leadership development: reflections of five women higher education leaders during the Coronavirus pandemic of 2020

ABSTRACT

For an adult, non-traditional student focused college, the pandemic brought into stark reality the challenges that the dislocation brought ‘home,’ literally, for many people. This article presents a set of reflections of five women leaders at a public institution of higher education. Through their reflections, they discuss their responses to the challenges faced by faculty, staff and students during the pandemic. Issues of gender, race, class, precarious work, technological access, and related challenges are raised to the surface. We offer three implications for HRD and leadership development research and practice.     

Family Trajectories and Health: A Life Course Perspective

This paper investigates the role of family trajectory, i.e., the whole sequence of family events during the life course of early adults in shaping their health outcomes. Union formation and childbearing are jointly considered, since the two life domains are highly connected and their intersections may have an effect on health outcomes. Data come from wave I and wave IV of the National Longitudinal Study of Adolescent Health (Add Health) in the United States. The paper is divided in two parts. The first part focuses on family transitions and investigates if changes in timing (when events happen), quantum (what and how many transitions), and ordering (in what order), have an effect on the health of young women. In the second part, life course trajectories are classified into six groups representing different ideal-types of family trajectories and the association of these trajectories with health outcomes is explored. Results suggest that family trajectories play an important role on different health outcomes. Controlling for selection and background characteristics, precocious and “non-normative” transitions are associated with lower self-reported health and higher propensity of smoking and drinking.     

Illegitimate tasks as a source of work stress

Illegitimate tasks represent a task-level stressor derived from role and justice theories within the framework of “Stress-as–Offense-to-Self” (SOS; Semmer, Jacobshagen, Meier, & Elfering, 2007). Tasks are illegitimate if they violate norms about what an employee can properly be expected to do, because they are perceived as unnecessary or unreasonable; they imply a threat to one's professional identity. We report three studies testing associations between illegitimate tasks and well-being/strain. In two cross-sectional studies, illegitimate tasks predicted low self-esteem, feelings of resentment towards one's organization and burnout, controlling for role conflict, distributive injustice and social stressors in Study 1, and for distributive and procedural/interactional justice in Study 2. In Study 3, illegitimate tasks predicted two strain variables (feelings of resentment towards one's organization and irritability) over a period of two months, controlling for initial values of strain. Results confirm the unique contribution of illegitimate tasks to well-being and strain, beyond the effects of other predictors. Moreover, Study 3 demonstrated that illegitimate tasks predicted strain, rather than being predicted by it. We therefore conclude that illegitimate tasks represent an aspect of job design that deserves more attention, both in research and in decisions about task assignments.     

Inference from PseudoLikelihoods with Plug‐In Estimates

Effective implementation of likelihood inference in models for high‐dimensional data often requires a simplified treatment of nuisance parameters, with these having to be replaced by handy estimates. In addition, the likelihood function may have been simplified by means of a partial specification of the model, as is the case when composite likelihood is used. In such circumstances tests and confidence regions for the parameter of interest may be constructed using Wald type and score type statistics, defined so as to account for nuisance parameter estimation or partial specification of the likelihood. In this paper a general analytical expression for the required asymptotic covariance matrices is derived, and suggestions for obtaining Monte Carlo approximations are presented. The same matrices are involved in a rescaling adjustment of the log likelihood ratio type statistic that we propose. This adjustment restores the usual chi‐squared asymptotic distribution, which is generally invalid after the simplifications considered. The practical implication is that, for a wide variety of likelihoods and nuisance parameter estimates, confidence regions for the parameters of interest are readily computable from the rescaled log likelihood ratio type statistic as well as from the Wald type and score type statistics. Two examples, a measurement error model with full likelihood and a spatial correlation model with pairwise likelihood, illustrate and compare the procedures. Wald type and score type statistics may give rise to confidence regions with unsatisfactory shape in small and moderate samples. In addition to having satisfactory shape, regions based on the rescaled log likelihood ratio type statistic show empirical coverage in reasonable agreement with nominal confidence levels.     

From wage rigidity to labour market institution rigidity: A turning-point in explaining unemployment?

In this paper we offer a critical discussion about the concept of labour market rigidity in the light of recent theoretical approaches that have aimed to provide sound micro-foundations to the presence of unemployment in market economies. We point out that the concept of labour market rigidity usually referred to in such theories has changed over time, involving in succession the rigidity of wages, contracts and labour market institutions. We also appraise the factors that lead labour market institutions rigidity, stressed by the search literature, to challenge the more widespread explanation of unemployment grounded on wage rigidity. Moreover, we analyse some theoretical and empirical issues that cast doubt on the ability to deal with unemployment, disentangling the role of institutional rigidities from that of wage stickiness.     

Knowledge Diversity and Venture Growth: The Contingent Effects of Early Planning and Experimentation

Drawing on an information processing perspective, we explore to what extent early venture activities allow founding teams to leverage their diverse knowledge to achieve venture growth. Using data from 103 young ventures, we find that early planning enables founding teams to better exploit the diverse knowledge resulting from their heterogeneity in educational background. However, venture growth is highest when diverse teams simultaneously plan and experiment in the early venture phase. This study challenges extant explanations of when early behaviours shape the efficient usage of existing venture resources. We discuss the contribution of these findings to the literature on founding teams, planning and experimentation, and team diversity.     

Let's stay close: An examination of the effects of imagined contact on behavior toward children with disability

In line with current developments in indirect intergroup contact literature, we conducted a field study using the imagined contact paradigm among high-status (Italian children) and low-status (children with foreign origins) group members (N = 122; 53 females, mean age = 7.52 years). The experiment aimed to improve attitudes and behavior toward a different low-status group, children with disability. To assess behavior, we focused on an objective measure that captures the physical distance between participants and a child with disability over the course of a five-minute interaction (i.e., while playing together). Results from a 3-week intervention revealed that in the case of high-status children imagined contact, relative to a no-intervention control condition, improved outgroup attitudes and behavior, and strengthened helping and contact intentions. These effects however did not emerge among low-status children. The results are discussed in the context of intergroup contact literature, with emphasis on the implications of imagined contact for educational settings.     

An Integrated Approach to Select Key Quality Indicators in Transit Services

Social Indicators Research - Recent interests in transit services have captured attention of experts on the monitoring of public transport quality. Previous research focused on relevant models and...