Bayesian inference in a correlated random coefficients model: Modeling causal effect heterogeneity with an application to heterogeneous returns to schooling

We consider the problem of causal effect heterogeneity from a Bayesian point of view. This is accomplished by introducing a three-equation system, similar in spirit to the work of Heckman and Vytlacil (1998), describing the joint determination of a scalar outcome, an endogenous “treatment” variable, and an individual-specific causal return to that treatment. We describe a Bayesian posterior simulator for fitting this model which recovers far more than the average causal effect in the population, the object which has been the focus of most previous work. Parameter identification and generalized methods for flexibly modeling the outcome and return heterogeneity distributions are also discussed.Combining data sets from High School and Beyond (HSB) and the 1980 Census, we illustrate our methods in practice and investigate heterogeneity in returns to education. Our analysis decomposes the impact of key HSB covariates on log wages into three parts: a “direct” effect and two separate indirect effects through educational attainment and returns to education. Our results strongly suggest that the quantity of schooling attained is determined, at least in part, by the individual’s own return to education. Specifically, a one percentage point increase in the return to schooling parameter is associated with the receipt of (approximately) 0.14 more years of schooling. Furthermore, when we control for variation in returns to education across individuals, we find no difference in predicted schooling levels for men and women. However, women are predicted to attain approximately 1/4 of a year more schooling than men on average as a result of higher rates of return to investments in education.     

Validating an innovative real-time Delphi approach - A methodological comparison between real-time and conventional Delphi studies

A novel and innovative real-time Delphi technique is introduced in order to address previously identified weaknesses of the conventional Delphi method, such as complicated facilitator tasks, lack of real-time presentation of results, and difficulties in tracking progress over time. We demonstrate how the real-time (computer-based) method increases the efficiency of the process, accommodates expert availability, and reduces drop-out-rates. Modifications in the Delphi procedure (e.g. change of iteration principle) not only increase efficiency but also change the nature and process of the survey technique itself. By identifying and analysing three individual effects (initial condition effect, feedback effect, and iteration effect) we examine whether the modifications in the survey process cause deviations to the survey results. Empirical data obtained from both conventional as well as real-time Delphi studies is analysed based on multiple statistical analyses. The research findings indicate that significant differences between the two Delphi survey formats do not exist and final survey results are not affected by changes in the survey procedure.     

Prävention und Management von Staatsinsolvenzen in der Europäischen Währungsunion

Der Umgang mit den Schuldenkrisen in einigen Eurol?ndern steht derzeit ganz oben auf der Tagesordnung der EWU-Gremien. Der Rettungsschirm zur aktuellen Krisenbew?ltigung ist allerdings bis 2013 befristet. Danach sollte ein dauerhafter Krisenpr?ventions- und Krisenmanagementmechanismus eingesetzt werden. Wie ein solcher Mechanismus zu gestalten ist, erl?utern die Autoren in diesem Beitrag.     

The paradox of tie strength in customer relationships for innovation: a longitudinal case study in the sports industry

Current literature argues that firms should have strong ties to customers to benefit from increased customer retention and loyalty. Strong ties, however, have also shown to prevent innovation, suggesting that firms should also develop weak ties to other customer groups. This paper focuses on the potential for strong ties to facilitate, rather than prohibit, innovation. It is based in a 7‐year longitudinal research project with Adidas, a global sporting goods company. From the case, we find that the paradox of tie strength results from an overly simplified view of the nature of company–customer relationships. Contrary to the established literature, we find that strong ties in the Adidas case supported significant innovation. In fact, the involvement resulted in the development of a new product with a radically different product architecture and led to one of the most successful product launches in the company's history. To explain these findings, we introduce the nature of customer participation in a firm's value creation processes as a new dimension of the constitution of firm–customer ties and discuss how such a kind of relationship can develop.     

Are family‐friendly workplace practices a valuable firm resource?

We study the determinants and consequences of family‐friendly workplace practices (FFWP) using a sample of over 450 manufacturing firms in Germany, France, U.K., and U.S. We find a positive correlation between firm productivity and FFWP. This association disappears, however, once we control for a measure of the quality of management practices. We further find that firms with a higher proportion of female managers and more skilled workers, as well as well‐managed firms, tend to implement more FFWP. Conversely, a firm's environment does not have a significant impact on the FFWP it provides. © 2010 The Authors. Strategic Management Journal published by John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.     

Toward a theory of transformative entrepreneuring: Poverty reduction and conflict resolution in Rwanda's entrepreneurial coffee sector

This study illustrates how entrepreneurship may catalyze prosperity as well as peace in entrenched poverty–conflict zones. We bring to life a conceptualization of transformative entrepreneuring by assessing interrelationships between poverty and conflict indicators from the perspective of rural dwellers in Rwanda's entrepreneurial coffee sector. Our findings suggest that individuals' perceptions of poverty alleviation and conflict reduction are sequentially linked, notably via increased quality of life. This enables us to advance theory on entrepreneuring by unpacking the mechanisms through which entrepreneurial processes may transform the lives of such ‘ordinary’ entrepreneurs in settings where economic and social value creation are desperately needed.     

Semiparametric Bayesian inference in multiple equation models

This paper outlines an approach to Bayesian semiparametric regression in multiple equation models which can be used to carry out inference in seemingly unrelated regressions or simultaneous equations models with nonparametric components. The approach treats the points on each nonparametric regression line as unknown parameters and uses a prior on the degree of smoothness of each line to ensure valid posterior inference despite the fact that the number of parameters is greater than the number of observations. We develop an empirical Bayesian approach that allows us to estimate the prior smoothing hyperparameters from the data. An advantage of our semiparametric model is that it is written as a seemingly unrelated regressions model with independent normal–Wishart prior. Since this model is a common one, textbook results for posterior inference, model comparison, prediction and posterior computation are immediately available. We use this model in an application involving a two‐equation structural model drawn from the labour and returns to schooling literatures. Copyright © 2005 John Wiley & Sons, Ltd.