City networks and commodity chains: identifying global flows and local connections in Ho Chi Minh City

Any analytical framework for understanding actual forms of the intensified incorporation of cities into the world economy needs to go beyond the exclusive focus on advanced producer services, which is characteristic of most of the World City Network (WCN) approach. Simultaneously, an account of the role of advanced producer services will strengthen Global Commodity Chain (GCC) analysis. A combination of the literatures on WCN and GCC can contribute to a broader conceptualization of the connections and connectivities of global cities. In addition, a combined approach will improve our understanding of globalization processes within many so-called 'third-world' cities that are experiencing booms in export-oriented industrialization and in migration from rural hinterlands as they are being integrated into Global Commodity Chains. We illustrate our argument with insights from GCC analyses of the electronics industry located in Ho Chi Minh City and the agricultural sector in its rural hinterland, the Mekong Delta.     

A Stochastic Geometry Model for Functional Magnetic Resonance Images

In functional magnetic resonance imaging, spatial activation patterns are commonly estimated using a non-parametric smoothing approach. Significant peaks or clusters in the smoothed image are subsequently identified by testing the null hypothesis of lack of activation in every volume element of the scans. A weakness of this approach is the lack of a model for the activation pattern; this makes it difficult to determine the variance of estimates, to test specific neuroscientific hypotheses or to incorporate prior information about the brain area under study in the analysis. These issues may be addressed by formulating explicit spatial models for the activation and using simulation methods for inference. We present one such approach, based on a marked point process prior. Informally, one may think of the points as centres of activation, and the marks as parameters describing the shape and area of the surrounding cluster. We present an MCMC algorithm for making inference in the model and compare the approach with a traditional non-parametric method, using both simulated and visual stimulation data. Finally we discuss extensions of the model and the inferential framework to account for non-stationary responses and spatio-temporal correlation.     

The Current Duration Approach to Estimating Time to Pregnancy

Abstract. Time‐to‐pregnancy (TTP) is the duration from the time a couple starts trying to become pregnant until they succeed. It is considered one of the most direct methods to measure natural fecundity in humans. Statistical tools for designing and analysing time to pregnancy studies belong to survival analysis, but several features require special attention. Prospective designs are difficult to carry out and retrospective (pregnancy‐based) designs, being widely used in this area, do not allow efficiently including couples remaining childless. A third possible design starts from a cross‐sectional sample of couples currently trying to become pregnant, using current duration (backward recurrence time) as basis for the estimation of TTP. Regression analysis is then most conveniently carried out in the accelerated failure time model. This paper surveys some practical and technical‐statistical issues in implementing this approach in a large telephone‐based survey, the Epidemiological Observatory of Fecundity in France (Obseff).     

Competition in online job marketplaces: towards a global labour market for outsourcing services?

A new form of service outsourcing has emerged, namely the global online job marketplace for freelance contractors. Such platforms are currently the closest proxy to the idea of a global labour market where everyone competes for jobs regardless of location. In this article, we examine how competition manifests itself on one such global online platform, namely oDesk. We present a comparative analysis of the relative wages and the rewarding of skills and expertise of contractors from selected countries and investigate whether, via labour arbitrage, wage convergence takes place between Western and developing countries. We find that wage convergence is noticeable but experience and skills hardly translate into better remuneration. While service outsourcing (or microwork) via global online marketplaces provides new employment opportunities for freelancers around the world, the intense competition and the inherent restrictions of this type of marketplace limit the financial gains for most contractors.