Selection of influential variables in ordinal data with preponderance of zeros

Presence of excess zero in ordinal data is pervasive in areas like medical and social sciences. Unfortunately, analysis of such kind of data has so far hardly been looked into, perhaps for the reason that the underlying model that fits such data, is not a generalized linear model. Obviously some methodological developments and intensive computations are required. The current investigation is concerned with the selection of variables in such models. In many occasions where the number of predictors is quite large and some of them are not useful, the maximum likelihood approach is not the automatic choice. As, apart from the messy calculations involved, this approach fails to provide efficient estimates of the underlying parameters. The proposed penalized approach includes ?₁ penalty (LASSO) and the mixture of ?₁ and ?₂ penalties (elastic net). We propose a coordinate descent algorithm to fit a wide class of ordinal regression models and select useful variables appearing in both the ordinal regression and the logistic regression based mixing component. A rigorous discussion on the selection of predictors has been made through a simulation study. The proposed method is illustrated by analyzing the severity of driver injury from Michigan upper peninsula road accidents.     

Optimal risk taking in an uneven tournament game with risk averse players

We analyze the optimal choice of risk in a two-stage tournament game between two players that have different concave utility functions. At the first stage, both players simultaneously choose risk. At the second stage, both observe overall risk and simultaneously decide on effort or investment. The results show that those two effects which mainly determine risk taking – an effort effect and a likelihood effect – are strictly interrelated. This finding sharply contrasts with existing results on risk taking in tournament games with symmetric equilibrium efforts where such linkage can never arise. Conditions are derived under which this linkage leads to a reversed likelihood effect so that the favorite (underdog) can increase his winning probability by increasing (decreasing) risk which is impossible in a completely symmetric setting.     

Revisiting the relationship between suicide and unemployment: Evidence from linear and nonlinear cointegration

This study employs the linear and nonlinear ARDL cointegration methodologies to examine the potential symmetric and asymmetric responses of suicide rates to unemployment rates in the US from 1928 to 2013. Our results suggest that suicide rates are pro-cyclical with respect to the business cycle (measured by changes in the unemployment rate) after extensively controlling for divorce and fertility rates. Unemployment has symmetric long-run effects on the age-adjusted suicide rate and four age-specific (from ages 25–34 to 55–64) suicide rates, while the effect of an economic expansion on suicide rates for those aged over 45 is greater than the effect of an economic recession. These findings imply that the effect of an economic expansion on the decrease of the suicide rate is higher than the effect of an economic recession on the increase of the suicide rate for individuals aged over 45. Therefore, intervention designed to reduce suicidal behaviors should emphasize periods of economic recession more than periods of economic expansion for those of middle age and beyond.     

2＋1模式下高职毕业论文中存在的问题及对策--以浙江汽车职业技术学院物流管理专业为例

文中从浙江汽车职业技术学院物流管理专业“2＋1”教学模式学出发,分析了造成毕业论文质量低下、抄袭严重的原因,并提出了对毕业论文管理模式改革的思考。     

Construction of D-optimal s 1 × s 2 × s 3 factorial designs using graph theory

In this paper, the maximum determinant of the associated 0-1 matrix in D-Optimal saturated main effect plans for 3× s_2 × s_3 factorials, is derived by the use of Graph theory and Combinatorics. The present work is related to a problem suggested by Chatterjee and Narasimhan (2002). Using the theoretical results, we also give the designs for s₃≥s₂ + 1. This research was supported by the State Scholarships Foundation of Greece.     

Competitive balance versus competitive intensity before a match: is one of these two concepts more relevant in explaining attendance? The case of the French football Ligue 1 over the period 2008–2011

The aim of this article is to investigate the determinants of attendance at French football Ligue 1 matches over the period 2008–2011 with an emphasis on examining the effects of both competitive balance and intensity before a match. Competitive balance is measured by the point difference between the two teams concerned by a match in the championship. Competitive intensity is measured by the point difference for the home team in relation to ranks with sporting stakes. Results show that competitive balance has an insignificant impact whereas competitive intensity has a significantly positive impact. Implications are drawn.     

TACKLING THE ENDOGENEITY OF FERTILITY IN THE STUDY OF WOMEN'S EMPLOYMENT IN DEVELOPING COUNTRIES: ALTERNATIVE ESTIMATION STRATEGIES USING DATA FROM URBAN BRAZIL

Abstract

Opinions differ about whether family structure, especially fertility, should be considered endogenous in models of behavior in developing countries. Faced with a dearth of good instruments, mainstream researchers often urge working in reduced form and, therefore, losing variables of policy interest or limiting the type of questions they ask to those where good instruments are available. Rather than treating endogeneity as a yes or no characteristic, we suggest instead that researchers consider the likely magnitude of endogeneity bias before moving to reduced form. Facing a situation where endogeneity bias is often presented as a concern but where we expect little endogeneity bias, we tackle endogeneity using multiple econometric techniques not available to the average researcher. We find support for our hypothesis that little bias arises due to the assumption of exogeneity of recent fertility in a model of women's employment.     

“SWEEPING THE HEAVENS FOR A COMET”: WOMEN,THE LANGUAGE OF POLITICAL ECONOMY,AND HIGHER EDUCATION IN THE US

Abstract

The importance of increased levels of education in improving the status of women throughout the world is well established. Higher levels of education are associated with lower birth rates, higher incomes, and greater autonomy for women. Yet, women's struggle to have a voice in higher education has been fraught with difficulties in the US and worldwide, particularly in overcoming widely held perceptions that limit their entrance into certain academic fields, tenured positions, and elite universities. This essay examines the role political economy has played in providing narratives that rationalize women's limited participation in higher education. By examining the representation of women in the academic culture of the nineteenth- and twentieth-century US, we can perhaps better understand women's struggle to obtain an authoritative voice in higher education worldwide.     

Economic importance and statistical significance: Guidelines for communicating empirical research

Abstract

A critical objective for many empirical studies is a thorough evaluation of both substantive importance and statistical significance. Feminist economists have critiqued neoclassical economics studies for an excessive focus on statistical machinery at the expense of substantive issues. Drawing from the ongoing debate about the rhetoric of economic inquiry and significance tests, this paper examines approaches for presenting empirical results effectively to ensure that the analysis is accurate, meaningful, and relevant for the conceptual and empirical context. To that end, it demonstrates several measurement issues that affect the interpretation of economic significance and are commonly overlooked in empirical studies. This paper provides guidelines for clearly communicating two distinct aspects of “significance” in empirical research, using prose, tables, and charts based on OLS, logit, and probit regression results. These guidelines are illustrated with samples of ineffective writing annotated to show weaknesses, followed by concrete examples and explanations of improved presentation.     

The Challenge of Obtaining Quality Care: Limited Consumer Sovereignty in Human Services

Abstract

This paper offers a conceptual analysis of the problem of quality in human services: in elementary school, psychiatric care, and the health and social care of children, the elderly, and the intellectually disabled. Geriatric nursing home patients are used as a case. These care recipients cannot enforce their legal right to quality service; their quality-effective demand is low. Formal economic analyses often characterize the weak position of the care recipient as an information asymmetry problem. An additional obstacle, however, is the recipient's inability to safeguard her personal interest due to physical, mental, or social incapacities; that is, “limited consumer sovereignty.” Incapacitated individuals cannot enforce quality even when quality information is available. This creates a fundamental incentive problem in the monitoring of quality. They also depend on services that are complex and non-verifiable, making external monitoring difficult. This paper presents a typology of measures to increase the quality pressure facing providers.