Empirical Bayes models of Poisson clinical trials and sample size determination

Bayesian methods are often used to reduce the sample sizes and/or increase the power of clinical trials. The right choice of the prior distribution is a critical step in Bayesian modeling. If the prior not completely specified, historical data may be used to estimate it. In the empirical Bayesian analysis, the resulting prior can be used to produce the posterior distribution. In this paper, we describe a Bayesian Poisson model with a conjugate Gamma prior. The parameters of Gamma distribution are estimated in the empirical Bayesian framework under two estimation schemes. The straightforward numerical search for the maximum likelihood (ML) solution using the marginal negative binomial distribution is unfeasible occasionally. We propose a simplification to the maximization procedure. The Markov Chain Monte Carlo method is used to create a set of Poisson parameters from the historical count data. These Poisson parameters are used to uniquely define the Gamma likelihood function. Easily computable approximation formulae may be used to find the ML estimations for the parameters of gamma distribution. For the sample size calculations, the ML solution is replaced by its upper confidence limit to reflect an incomplete exchangeability of historical trials as opposed to current studies. The exchangeability is measured by the confidence interval for the historical rate of the events. With this prior, the formula for the sample size calculation is completely defined. Published in 2009 by John Wiley & Sons, Ltd.     

Employment‐Housing Paradigm of Internal Migration: Evidence from Norway

In a previous article (Portnov, 1999), the employment‐housing paradigm of interregional migration was introduced. According to this paradigm, different patterns of employment‐housing change in various geographic areas are likely to result in three different migration events – predominant in migration, out‐migration or “migration neutrality”. The latter is considered as a state of equilibrium in which a region or community neither gains nor loses its population in migration exchanges with other areas. Using preconditions for such migration neutrality as a “reference line”, planners and decision‐makers can determine regional policies aimed at a more balanced distribution of a country's population through generating a “migration push” in overpopulated regions and encouraging inward migration to development areas in which population growth is desirable. In the present article, the validity of this concept is tested using 1970‐89 statistical data for 430 municipalities in Norway. It appeared feasible to separate the band of migration neutrality from other migration cases and establish the quantitative thresholds of employment‐housing change that are conducive to the occurrence of different migration events – migration neutrality, in‐migration and out‐migration.     

Bayesian design and analysis of composite endpoints in clinical trials with multiple dependent binary outcomes

The author considers studies with multiple dependent primary endpoints. Testing hypotheses with multiple primary endpoints may require unmanageably large populations. Composite endpoints consisting of several binary events may be used to reduce a trial to a manageable size. The primary difficulties with composite endpoints are that different endpoints may have different clinical importance and that higher‐frequency variables may overwhelm effects of smaller, but equally important, primary outcomes. To compensate for these inconsistencies, we weight each type of event, and the total number of weighted events is counted. To reflect the mutual dependency of primary endpoints and to make the weighting method effective in small clinical trials, we use the Bayesian approach. We assume a multinomial distribution of multiple endpoints with Dirichlet priors and apply the Bayesian test of noninferiority to the calculation of weighting parameters. We use composite endpoints to test hypotheses of superiority in single‐arm and two‐arm clinical trials. The composite endpoints have a beta distribution. We illustrate this technique with an example. The results provide a statistical procedure for creating composite endpoints. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

The Worth of Life and the Limits of Law

Survey data show that for Russians the most heinous crimes are serial murder, rape of minors, and premeditated murder, and these are the crimes for which they most often demand the death penalty. Four out of five say the Russian system of justice is guilty of mistakes often and very often, yet almost half of Russians are in favor of reinstituting and expanding the practical imposition of the death penalty     

Return to Education and the Changing Role of Credentials in the Croatian Labor Market

The countries of Central and Eastern Europe experienced a rapid increase of return to education with the advent of the transition. We look at the dynamics of wage premiums in Croatia and estimate how much the return to education has changed between 1996 and 2004 on the basis of labor force survey data. We also extend the paper in order to address additional features of the wage structure, such as non-linearities in the return to education associated with attainment of credentials. We find that contrary to most transition countries, premiums for education in Croatia began to grow only after the mid 1990s. However, by 2004, they reached the levels of premiums found in other transition countries and advanced market economies, thus creating market incentives for investment in education. We also find that major part of this higher rate of return came through higher return to credentials.

Authors’ response

In this rejoinder, we address all or almost all comments that have been provided by the discussants. In particular, we include additional references to literature related to change-point detection as well as to intrusion detection; analyze distributions of stopping times of the CUSUM and Shiryaev–Roberts detection procedures under the no change hypothesis in more detail; and provide an overview of the detection-isolation problem.     

Roads and Diversification of Activities in Rural Areas: A Cameroon Case Study

This article uses the 2001 Cameroon National Household Survey (ECAM II) to analyse how road access affects labour activities. It shows that one‐size‐fits‐all road investments are irrelevant because the effects of roads are neither systematic nor uniform: the impacts of isolation on household well‐being through labour‐market opportunities are heterogeneous and depend on local characteristics. In view of the diversification of activities in household strategy, it finds that better road access increases the number of activities within those households that are most isolated.     

Towards a theorisation of diversity. Configurations of person-related differences in the context of youth welfare practices

ABSTRACT

The article proposes a pathway towards a theorisation of diversity. It is argued that diversity can be understood as referring to the complex outcomes of multifaceted processes in which various schemes of classifications are applied to persons and segments of populations. A growing interest in individuals and their qualities, combined with the development of information technologies, has stimulated a proliferation of person-related categories. Diversity offers an analytical lens for studying the relational qualities of various person-related differences, the interaction between categories of different scale and scope and their situational organisation. Thereby, it goes beyond notions of identity, on the one hand, and intersectionality, on the other. In the second part of the article, the outlined framework is applied to the cases of youth welfare practice in Stuttgart and Frankfurt. The focus of the case analysis is migration-related categories and how they relate to larger configurations of person-related differences in the field of youth welfare practice. It is argued that a diversity perspective, as suggested here, allows us to capture an element of opaqueness and ambiguity concerning migration-related differentiations that has implications for the understanding of ongoing debates about discrimination and racialisation.