Efficient circular neighbour designs for spatial interference model

We consider circular block designs for field-trials when there are two-sided spatial interference between neighbouring plots of the same blocks. The parameter of interest is total effects that is the sum of direct effect of treatment and neighbour effects, which correspond to the use of a single treatment in the whole field. We determine universally optimal approximate designs. When the number of blocks may be large, we propose efficient exact designs generated by a single sequence of treatment. We also give efficiency factors of the usual binary block neighbour balanced designs which can be used when the number of blocks is small.     

An adaptive sequential Monte Carlo method for approximate Bayesian computation

Approximate Bayesian computation (ABC) is a popular approach to address inference problems where the likelihood function is intractable, or expensive to calculate. To improve over Markov chain Monte Carlo (MCMC) implementations of ABC, the use of sequential Monte Carlo (SMC) methods has recently been suggested. Most effective SMC algorithms that are currently available for ABC have a computational complexity that is quadratic in the number of Monte Carlo samples (Beaumont et al., Biometrika 86:983?C990, 2009; Peters et al., Technical report, 2008; Toni et al., J.?Roy. Soc. Interface 6:187?C202, 2009) and require the careful choice of simulation parameters. In this article an adaptive SMC algorithm is proposed which admits a computational complexity that is linear in the number of samples and adaptively determines the simulation parameters. We demonstrate our algorithm on a toy example and on a birth-death-mutation model arising in epidemiology.     

Social Movements and Europeanization Processes: The Case of the French Associations Mobilizing around the Asylum Issue

This paper seeks to analyse the process of Europeanization of social movements mobilizing around the asylum policy since the middle of the 1990s. Taking the example of the principal French associations which have mobilized on this topic, the paper explores the dynamics that lead these associations to increasingly address the European institutions since the launching of the process of harmonisation of asylum policies. In particular, it shows that particular attention shall be given to the relationship between the associations that have constituted at the national level and the set of actors that are mobilized on this issue exclusively at the European level (which is defined as a European advocacy coalition). Through the analysis of this relationship, it can be seen that the French associations follow different processes of Europeanization. Some follow a process of inclusion into the existing European advocacy coalition while others create alternative mobilizations at the European level. This study allows us to observe and to analyse the similarities and differences in the interactions between social movements and institutions in the national political space and in the European political space on this particular issue. In doing so, it seeks to present an original perspective on a process of ‘Europeanization from below’. This research is based on the in-depth analysis of 11 associations which are representative of the diversity of the movement related to the asylum issue in France. It uses different methods that were developed in social movements studies: frame analysis, protest-event analysis and network analysis. It is based on several sources: associative discourses and publications, in-depth interviews, and associative internal literature.     

When outsourcing fragments: customer creativity and technological transmutations

One of the most fundamental decisions made in firms is about what functions or activities the firm should perform within its own hierarchy, and which of these it should rely on the market to perform. Outsourcing is ‘an agreement in which one company contracts out a part of their existing internal activity to another company’. However, this article contends that outsourcing has changed, and is changing in ways that make the application of neat, legal and technically correct definitions hard to use, and even harder to apply in strategy. Under the new outsourcing paradigm, technology is not a passive ‘substance’, rather it is an active ‘force’. We aim to look at the ways in which technologies are re-shaped and transmuted by consumers. Through this analysis, we add the consumer activity to the conventional definition of outsourcing. We focus on one of the most highly anticipated and influential new products of 2007 – the Apple iPhone.     

On testing for independence between the innovations of several time series

Test statistics for checking the independence between the innovations of several time series are developed. The time series models considered allow for general specifications for the conditional mean and variance functions that could depend on common explanatory variables. In testing for independence between more than two time series, checking pairwise independence does not lead to consistent procedures. Thus a finite family of empirical processes relying on multivariate lagged residuals are constructed, and we derive their asymptotic distributions. In order to obtain simple asymptotic covariance structures, Möbius transformations of the empirical processes are studied, and simplifications occur. Under the null hypothesis of independence, we show that these transformed processes are asymptotically Gaussian, independent, and with tractable covariance functions not depending on the estimated parameters. Various procedures are discussed, including Cramér–von Mises test statistics and tests based on non‐parametric measures. The ranks of the residuals are considered in the new methods, giving test statistics which are asymptotically margin‐free. Generalized cross‐correlations are introduced, extending the concept of cross‐correlation to an arbitrary number of time series; portmanteau procedures based on them are discussed. In order to detect the dependence visually, graphical devices are proposed. Simulations are conducted to explore the finite sample properties of the methodology, which is found to be powerful against various types of alternatives when the independence is tested between two and three time series. An application is considered, using the daily log‐returns of Apple, Intel and Hewlett‐Packard traded on the Nasdaq financial market. The Canadian Journal of Statistics 40: 447–479; 2012 © 2012 Statistical Society of Canada     

Predictors of the emergence of transformational leadership in virtual decision teams

This study examined the etiology of transformational leadership in virtual team contexts. First, we compared 127 members of virtual decision-making teams with 135 members of traditional face-to-face teams in terms of the relationship between aspects of personality and the emergence of transformational leadership. The type of communication media (face-to-face versus “pure” virtual) was found to interact with extraversion and emotional stability in the prediction of emerging transformational leadership. In line with prior findings, we showed how these personality characteristics were relevant to transformational leadership emergence in our face-to-face teams. However, they were largely unrelated to such leadership in the virtual team context. We also focused specifically on the virtual context by analyzing the content of team interactions. After accounting for the effect of degree of activity level, the linguistic quality in one's written communication was found to predict the emergence of transformational leadership in virtual teams.