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.     

Kurtosis modelling by means of the J-transformation

Summary: The H–family of distributions or H–distributions, introduced by Tukey (1960; 1977), are generated by a single transformation of the standard normal distribution and allow for leptokurtosis represented by the parameter h. Alternatively, Haynes et al. (1997) generated leptokurtic distributions by applying the K–transformation to the normal distribution. In this study we propose a third transformation, the so–called J–transformation, and derive some properties of this transformation. Moreover, so-called elongation generating functions (EGFs) are introduced. By means of EGFs we are able to visualize the strength of tail elongation and to construct new transformations. Finally, we compare the three transformations towards their goodness–of–fit in the context of financial return data.     

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.     

Social determinants of life expectancy]

"Life expectancy and mortality increasingly are analyzed in the context of social factors. This study analyzes the impact of social position, marital status, and religious confession on cohort life expectancy. The analysis is based on [German data from the] Socio-Economic Panel Survey, wherein proxy-interviewee's parents have been used to estimate cohort mortality. Results confirm a lower mortality risk of the upper classes and of married persons. However, as opposed to other studies, Catholics do not have a lower, but even a higher mortality risk." (SUMMARY IN ENG)     

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.