A Note on the Role of the Propensity Score for Estimating Average Treatment Effects

Hahn [Hahn, J. (1998). On the role of the propensity score in efficient semiparametric estimation of average treatment effects. Econometrica 66:315-331] derived the semiparametric efficiency bounds for estimating the average treatment effect (ATE) and the average treatment effect on the treated (ATET). The variance of ATET depends on whether the propensity score is known or unknown. Hahn attributes this to “dimension reduction.” In this paper, an alternative explanation is given: Knowledge of the propensity score improves upon the estimation of the distribution of the confounding variables.     

The global clothing production system: commodity chains and business networks

The global organization of the clothing industry has been the prime example of buyer‐driven commodity chains. However, previous empirical studies to substantiate Gereffi's assertion have been highly Western centric and predominantly based on the empirical evidence of American retailers and brand name companies. In this article I demonstrate that any clothing commodity chain has various influential factors, such as the national and global regulatory framework, the societal context of the leading firm, the fashion context of the products, as well as the actual brand ownership. Thus, the organization of clothing firms in the global economy can develop diverse intra‐sectoral commodity chain coordinations. Using a hypothetical clothing commodity chain as an example, I attempt to identify the individual commodity chains within which Indonesian clothing firms are embedded. Furthermore, I outline the ways in which Indonesian clothing firms were affected by the economic crisis of the late 1990s.     

Correlates of honor ratings in a clinical clerkship employing a faculty forum evaluation system

5he purpose of this study was to determine whether or not suspected variables affected a surgery clerk's chances of being awarded an honor rating. Findings indicated a significant relationship between a student receiving an honor rating and his or her preceptor's predetermined level of student advocacy, the number of completed patient interview and physical examination write-ups, and final examination scores. There was no significant relationship found between honor ratings and the preceptor's status, the sequence in which the student was discussed or the length of time spent discussing the student at the final evaluation meeting, or the number of clinical faculty present at the meeting. These results lend support to the faculty forum evaluation approach, but suggest a need for further scrutiny of some influencing variables to ensure all students are fairly considered and honor ratings judiciously awarded.     

Permuting incomplete paired data: a novel exact and asymptotic correct randomization test

Various statistical tests have been developed for testing the equality of means in matched pairs with missing values. However, most existing methods are commonly based on certain distributional assumptions such as normality, 0-symmetry or homoscedasticity of the data. The aim of this paper is to develop a statistical test that is robust against deviations from such assumptions and also leads to valid inference in case of heteroscedasticity or skewed distributions. This is achieved by applying a clever randomization approach to handle missing data. The resulting test procedure is not only shown to be asymptotically correct but is also finitely exact if the distribution of the data is invariant with respect to the considered randomization group. Its small sample performance is further studied in an extensive simulation study and compared to existing methods. Finally, an illustrative data example is analysed.     

Adaption agiler Prinzipien für den Hochschulkontext am Beispiel des Universitätskollegs der Universität Hamburg

This report on practice discusses the pertinence of agile principles on the basis of the case “Universitätskolleg”, a central organisational unit of Universität Hamburg to promote the quality of studies and teaching. It describes previous experience with the framework scrum and the method Lean Kanban in mind. Odds and challenges of agile principles in university context are described and reflected and next steps are named.     

Examining the association between Medicaid coverage and preterm births using 2010–2013 National Vital Statistics Birth Data

Reducing the number of preterm births is a high public health priority in the U.S. Preterm birth, affecting an estimated 380,000 infants annually, is a leading cause of infant mortality and morbidity and is associated with individual and systemic characteristics. Preterm birth is estimated to cost society $26 billion annually. Despite an elevated financial burden caused by preterm birth, very little is known about who bears these costs. This study seeks to understand the relationship between Medicaid and private insurance payment for preterm birth, using multiple years of vital statistics data, which for the first time since 2010 include information on payment source. The nationwide data cover births that occur in all settings, including non-hospital settings, and many maternal characteristics not available in other datasets, improving upon previous analyses. These data can be used to promote better Medicaid coverage of interventions known to be effective in reducing preterm births.     

“亚非地中海”——印度洋上的港口和城市网络

本文以全球化的视角和世界历史的视野,将研究的目光投向亚洲与非洲间的印度洋,并将其喻为"亚非地中海",将其视作一片海洋空间、跨国空间,视作一个交流的十字路口和一座不同文明间的桥梁。而"亚非地中海"上那些进行商业流与资金流的港口和城市网络,则构成了经济霸权的矩阵,并在"全球本土化"的进程中扮演着重要角色。它们的共存体现了相互竞争的同时性,地区和全球之间普世化和特殊化趋势的相互渗透。本文通过对《中等城市和城市网络》、《亚洲港口城市(公元1600-1800年)》、《亚洲的地中海》三部著作的阐述,详解了关于"亚非地中海"的学术研究。