Adaptive LASSO estimation for ARDL models with GARCH innovations

ABSTRACT

In this paper, we show the validity of the adaptive least absolute shrinkage and selection operator (LASSO) procedure in estimating stationary autoregressive distributed lag(p,q) models with innovations in a broad class of conditionally heteroskedastic models. We show that the adaptive LASSO selects the relevant variables with probability converging to one and that the estimator is oracle efficient, meaning that its distribution converges to the same distribution of the oracle-assisted least squares, i.e., the least square estimator calculated as if we knew the set of relevant variables beforehand. Finally, we show that the LASSO estimator can be used to construct the initial weights. The performance of the method in finite samples is illustrated using Monte Carlo simulation.     

Validation and Use of a Predictive Modeling Tool: Employing Scientific Findings to Improve Responsible Conduct of Research Education

Although recent evidence suggests ethics education can be effective, the nature of specific training programs, and their effectiveness, varies considerably. Building on a recent path modeling effort, the present study developed and validated a predictive modeling tool for responsible conduct of research education. The predictive modeling tool allows users to enter ratings in relation to a given ethics training program and receive instantaneous evaluative information for course refinement. Validation work suggests the tool’s predicted outcomes correlate strongly (r = 0.46) with objective course outcomes. Implications for training program development and refinement are discussed.     

The inclusion of ergonomic tools in the informational, conceptual and preliminary phases of the product design methodology

The process of product development has received special attention as it is being recognized as a source of competitive gain. Through its systematic use companies reduce costs, increase quality and decrease development time. However, one can find products being launched on the market that cause dissatisfaction to its users, and in consequence if the customer feels harmed or injured he will no longer purchase a product from the same brand. This in regard only to the commercial aspect; usually the danger of an accident or injury is not even thought about. This paper is the basis of the dissertation master's degree and used a literature research to build the repertoire, analyzing the methodologies applied by product design engineers, designers and ergonomists. The analysis results demonstrate the inefficiency of the design methodologies ergonomic issues. The contribution of this work lies in the suggestion to include ergonomic tools in all phases of product development and the presentation of a table with the tools that points out its most suitable time of application and results.     

Perspectives on Whistleblowing: Faculty Member Viewpoints and Suggestions for Organizational Change

Given the prevalence of unethical behavior in research, whistleblowing may serve an important policing function. Despite this potential value of whistleblowing to organizations, engaging in this type of activity often has negative ramifications for those who choose to blow the whistle. Organizations may fail to provide adequate support for these individuals. In order to help inform best practices for organizations in terms of whistleblowing support infrastructure, the present effort content analyzed interviews with university faculty members regarding ethical decision making in which whistleblowing was a topic. Relevant themes in these interviews are discussed.     

Typologies of substance use and illegal behaviors: A comparison of emerging adults with histories of foster care and the general population

This study used latent class analysis (LCA) to explore whether patterns of substance use and illegal behaviors among emerging adults, 18 to 28 years old, differ depending on whether they have a prior history in foster care. The study sample, consisting of 316 respondents who had previously been in foster care and 14,301 respondents without a foster care history, was drawn from the third wave of the National Longitudinal Study of Adolescent Health. A multiple-group LCA compared former foster youth to their peers in the general population. The following four classes were identified: illegal behaviors, substance use, illegal behaviors with problematic substance use and normative behaviors. Most of the differences between the groups were not statistically significant. However, within the illegal behavior class former foster youth were less likely to have bought, sold, or held stolen goods; injured someone in a fight so that she or he needed medical attention; to have sold drugs; and to have been drunk at school or work. Additionally, in the illegal behaviors with problematic substance use class emerging adults in the general population were more likely to have used cocaine. Within the normative behaviors class, former foster youth were more likely to be current smokers, and to have injured someone in a fight so that he or she required medical attention. Within the substance use class, emerging adults from the general population were more likely to have taken place in a fight where one group fought another. Additional statistically significant, but very small differences were also identified.     

A Note on Nonlinear Cointegration,Misspecification, and Bimodality

We derive the asymptotic distribution of the ordinary least squares estimator in a regression with cointegrated variables under misspecification and/or nonlinearity in the regressors. We show that, under some circumstances, the order of convergence of the estimator changes and the asymptotic distribution is non-standard. The t-statistic might also diverge. A simple case arises when the intercept is erroneously omitted from the estimated model or in nonlinear-in-variables models with endogenous regressors. In the latter case, a solution is to use an instrumental variable estimator. The core results in this paper also generalise to more complicated nonlinear models involving integrated time series.     

The Rich and the Poor: The Construction of an Affluence Line from the Poverty Line

The paper proposes a simple methodology to estimate an affluence line that depends on the knowledge of the income distribution and the poverty line for a given population. The idea that poverty is morally unacceptable and can be eradicated through redistribution of wealth provides the grounds for the methodology. The line is defined as the value that delimitates the aggregated income required to eradicate poverty by the way of transfers from the rich to the poor. I estimate an affluence line using Brazilian 1999 National Household Survey data and briefly discuss the results.     

Overview of Friedman’s Test and Post-hoc Analysis

When the null hypothesis of Friedman’s test is rejected, there is a wide variety of multiple comparisons that can be used to determine which treatments differ from each other. We will discuss the contexts where different multiple comparisons should be applied, when the population follows some discrete distributions commonly used to model count data in biological and ecological fields. Our simulation study shows that sign test is very conservative. Fisher’s LSD and Tukey’s HSD tests computed with ranks are the most liberal. Theoretical considerations are illustrated with data of the Azores Buzzard (Buteo buteo rothschildi) population from Azores, Portugal.