On the Spectral Decomposition in Normal Discriminant Analysis

This article enlarges the covariance configurations, on which the classical linear discriminant analysis is based, by considering the four models arising from the spectral decomposition when eigenvalues and/or eigenvectors matrices are allowed to vary or not between groups. As in the classical approach, the assessment of these configurations is accomplished via a test on the training set. The discrimination rule is then built upon the configuration provided by the test, considering or not the unlabeled data. Numerical experiments, on simulated and real data, have been performed to evaluate the gain of our proposal with respect to the linear discriminant analysis.     

Testing for Slope Heterogeneity Bias in Panel Data Models

ABSTRACT

Standard econometric methods can overlook individual heterogeneity in empirical work, generating inconsistent parameter estimates in panel data models. We propose the use of methods that allow researchers to easily identify, quantify, and address estimation issues arising from individual slope heterogeneity. We first characterize the bias in the standard fixed effects estimator when the true econometric model allows for heterogeneous slope coefficients. We then introduce a new test to check whether the fixed effects estimation is subject to heterogeneity bias. The procedure tests the population moment conditions required for fixed effects to consistently estimate the relevant parameters in the model. We establish the limiting distribution of the test and show that it is very simple to implement in practice. Examining firm investment models to showcase our approach, we show that heterogeneity bias-robust methods identify cash flow as a more important driver of investment than previously reported. Our study demonstrates analytically, via simulations, and empirically the importance of carefully accounting for individual specific slope heterogeneity in drawing conclusions about economic behavior.     

A new approach to truncated regression for count data

AStA Advances in Statistical Analysis - Standard Poisson and negative binomial truncated regression models for count data include the regressors in the mean of the non-truncated distribution. In...     

Aesthetics and organizations without walls

This paper is based on ethnographic research into European art photography conducted at the end of the 1980s. Its conceptual framework is the aesthetic approach to organization studies. It shows that art photography is an organization without walls. This is a new concept that may prove very fruitful to the study of organizations. It analyses the kind of organizations that are invisible to the observer, while at the same time it questions the conventional reading of organizational boundaries. The thesis of the paper is that the aesthetic experience is the glue which cements together and delimits art photography as an organization without walls, and that culture and symbolism are crucial elements in organizations without walls. This thesis is illustrated through the evocative construction of organizational knowledge using the aesthetic approach.     

Looking beneath and in-between the hidden surfaces: a critical review of defining,measuring and contextualizing mental health service disparities in the child welfare system

Efforts to understand and respond to racial and ethnic disparities in referrals to and use of mental health services among children involved in the child welfare system are constrained by the lack of consistency in defining and measuring disparities and the lack of clarity as to what causal mechanisms sustain patterns of disparate treatment. Recent developments in the field of public health offer some insight as to how our understanding of similar disparities in child welfare may be advanced. Despite advancements, there is still an insufficient knowledge base from which to offer an alternative definition of disparities that illuminates conceptual and methodological innovation in child welfare research. Based on a critical review of the literature, more exploratory and etiological research grounded in implementation of advanced metrics and multivariate methods is warranted to generate a clear definition. Recommendations are offered to address conceptual ambiguity.     

The impact of the term spread in US monetary policy from 1870 to 2013

In this paper, we apply a novel econometric approach joint with an exhaustive revision of the main events in the history of US monetary policy in order to check the effectiveness of monetary policy focused on interest rates. Unlike the traditional cointegration approach, this new methodology allows us to break with the rigidity of traditional approaches in favour of letting the series be cointegrated, and the spread is able to follow a long-memory process; i.e., it does not necessarily need to be I(0) and also rejects the assumption that interest rates could follow the dichotomy I(0)/I(1). To the best of our knowledge, this is one of the first applications of the Fractionally Cointegrated Vector Autoregressive (FCVAR) model (Johansen and Nielsen (2012) and Nielsen and Popiel (2016)). Aiming to achieve this goal, we use two databases, i.e., the Jordà-Schularick-Taylor Macrohistory Database and Shiller’s database. Our results cannot reject the Expectations Hypothesis of Term Structure in this time period, and more importantly, we also find that the long-term rate drives the long-run relationship, contributing to the total proportion to the common trend; the persistence of the spread shows us effective control power over interest rates by the Fed.     

Efficacy of a brief intervention on attitudes to reduce school violence: A randomized clinical trial

There is growing interest in the phenomenon of school violence, which has been associated in diverse works with youth's attitudes towards violence, and it has been the focus of many intervention programs. However, the high human and economic cost entailed can impede its administration in some school centers. Therefore, the goal of the present study is to assess the efficacy of a brief intervention aimed at modifying attitudes towards violence to reduce the phenomenon of school bullying. The sample was obtained from a Secondary Education Institute during the 2010–2011 school term, and was made up of 252 students aged between 12 and 15 years. A controlled and randomized design was used in order to assess the effects of the program “Count on Me.” Ten classrooms were randomly assigned either to the intervention or to a waiting-list. Results show a significant reduction of playground violence perceived by the students, especially among the girls. Implications for the development of future brief programs for the prevention of school violence are discussed.     

Games with capacity manipulation: incentives and Nash equilibria

Studying the interactions between preference and capacity manipulation in matching markets, we prove that acyclicity is a necessary and sufficient condition that guarantees the stability of a Nash equilibrium and the strategy-proofness of truthful capacity revelation under the hospital-optimal and intern-optimal stable rules. We then introduce generalized games of manipulation in which hospitals move first and state their capacities, and interns are subsequently assigned to hospitals using a sequential mechanism. In this setting, we first consider stable revelation mechanisms and introduce conditions guaranteeing the stability of the outcome. Next, we prove that every stable non-revelation mechanism leads to unstable allocations, unless restrictions on the preferences of the agents are introduced.     

Materialist Scholarship and The People of Puerto Rico

The People of Puerto Rico occupies an ambivalent place in both the genealogy of anthropological theory and the understanding of Puerto Rican society. Its co-authors collectively developed a uniform and complex conceptual scheme which expressed both convergence and divergence among them. The book furthered Marxist approaches in U.S. anthropology and was the first serious scholarly materialist analysis of Puerto Rico. While privileging the lives of common people, it fell short of representing important strains of Puerto Rican diversity and socio-historical dynamics. The Puerto Rico Social Anthropology Project used four different models to explain the genesis of cultural forms and the interrelations among aspects of society/culture, in a given, homogeneous, “subculture” or “socio-cultural segment” of a complex society. The Project's members stressed a linear-utilitarian analysis of these subcultures, but where they could not account for observed cultural forms with such an approach, they appealed to the culture-psychology relation. This article considers the four interlinked paradigms, the associated analysis of socio-cultural trends, the resulting problematic theoretical consequences, and the flawed Marxism of the work.