Testing Nowcast Monotonicity with Estimated Factors

This article proposes a test to determine whether “big data” nowcasting methods, which have become an important tool to many public and private institutions, are monotonically improving as new information becomes available. The test is the first to formalize existing evaluation procedures from the nowcasting literature. We place particular emphasis on models involving estimated factors, since factor-based methods are a leading case in the high-dimensional empirical nowcasting literature, although our test is still applicable to small-dimensional set-ups like bridge equations and MIDAS models. Our approach extends a recent methodology for testing many moment inequalities to the case of nowcast monotonicity testing, which allows the number of inequalities to grow with the sample size. We provide results showing the conditions under which both parameter estimation error and factor estimation error can be accommodated in this high-dimensional setting when using the pseudo out-of-sample approach. The finite sample performance of our test is illustrated using a wide range of Monte Carlo simulations, and we conclude with an empirical application of nowcasting U.S. real gross domestic product (GDP) growth and five GDP sub-components. Our test results confirm monotonicity for all but one sub-component (government spending), suggesting that the factor-augmented model may be misspecified for this GDP constituent. Supplementary materials for this article are available online.     

Maximum likelihood estimation of dirichlet distributions

Global concavity of the likelihood function is proved by means of an inequality involving the trigamma function. The computation of maximum likelihood estimates is discussed.     

Incomplete equalization: The effect of tracking in secondary education on educational inequality

This paper tests whether the existence of vocationally oriented tracks within a traditionally academically oriented upper education system reduces socioeconomic inequalities in educational attainment. Based on a statistical model of educational transitions and data on two entire cohorts of Danish youth, we find that (1) the vocationally oriented tracks are less socially selective than the traditional academic track; (2) attending the vocationally oriented tracks has a negative effect on the likelihood of enrolling in higher education; and (3) in the aggregate the vocationally oriented tracks improve access to lower-tier higher education for low-SES students. These findings point to an interesting paradox in that tracking has adverse effects at the micro-level but equalizes educational opportunities at the macro-level. We also discuss whether similar mechanisms might exist in other educational systems.     

Promoting the Health of Young Adults in Urban Public Universities: A Case Study From City University of New York

Abstract

Changing demographics of college students and new insights into the developmental trajectory of chronic diseases present universities with opportunities to improve population health and reduce health inequalities. The reciprocal relationships between better health and improved educational achievement also offer university health programs a chance to improve retention and graduation rates, a key objective for higher education. In 2007, City University of New York (CUNY), the nation's largest urban public university, launched Healthy CUNY, an initiative designed to offer life-time protection against chronic diseases and reduce health-related barriers to educational achievement. In its first 5 years, Healthy CUNY has shown that universities can mobilize students, faculty, and other constituencies to modify environments and policies that influence health. New policies on tobacco and campus food, enrollment of needy students in public food and housing assistance programs, and a dialogue on the role of health in academic achievement are first steps towards healthier universities.     

解线性不等式组的一个简便方法

本文应用线性代数的有关理论，提出了一个解线性不等式组的简便方法，并给出了一个判断不等式系统无解的充要条件。数值例子显示出所述方法的有效性。     

Socio-economic Indexes in Surveys for Comparisons between Countries

The study of socio-economic inequalities from across-national perspective has been hampered by the lack of adequate common indices of socio-economic status that can be used in a self-report survey instrument. This paper examines the construction and the properties of global social indexes in general, and of the Family Affluence Scale (henceforth FAS) in particular. The paper proposes a new strategy for making comparisons of the global index with stratified data, building a revised FAS based on Adapted Canonical Variate Analysis (henceforth ACVA). This alternative strategy for constructing a global index is available in standard software, and the new proposal for stratified data only requires a simple program, which is justified, explained and provided in the text. Data come from the 1998 Health Behaviour in School-Aged Children (HBSC), a WHO Cross-National Study using cluster sampling of schoolchildren from five countries: Denmark, Latvia, Portugal, Scotland and the USA. The results reveal that in every country we would have had a completely different evaluation of the three indicators of Family Affluence if we had used either linear or nonlinear approaches to compute the global indexes. Moreover, Family Affluence comparisons among countries shows that the relative contribution of the three indicators to the overall FAS, changes from country to country. We conclude that separate indicators of Family Affluence are not equally relevant in each country and, as a consequence, do not contribute equally to the global index. For cross-cultural studies, the strategy for constructing an index should be country specific. The methodological developments presented in the paper open up opportunities to study socio-economic patterning of health among young people in the developed world, since self completed surveys can now employ a common measure of family material wealth. The findings show that the RFAS (Revised FAS) is a useful index of socio-economic status for use in national and cross-national surveys of adolescent health and health behaviour. The new strategy for weighting observed indicators in the index gives it enhanced power to detect in equalities.