A graphical analysis of some basic results in social choice

We use a simple graphical approach to represent Social Welfare Functions that satisfy Independence of Irrelevant Alternatives and Anonymity. This approach allows us to provide simple and illustrative proofs of May's Theorem, of variants of classic impossibility results, and of a recent result on the robustness of Majority Rule due to Maskin (1995). In each case, geometry provides new insights on the working and interplay of the axioms, and suggests new results including a new characterization of the entire class of Majority Rule SWFs, a strengthening of May's Theorem, and a new version of Maskin's Theorem. Received: 31 July 1999/Accepted: 27 March 2001     

A body passes by: the flâneur and the senses in nineteenth-century London and Paris

Abstract

The flâneur is well-known for being the most emblematic nineteenth-century observer of urban life. Critics have often compared the flâneur to a camera eye which records everything and insisted on the predominance of sight over other senses in the cognitive process. This article emphasises the embodiedness of the flâneur’s vision, which is an experience of all the senses. Urban public space can be envisaged as a ‘metabolic space,’ in which “the links between background and figures are very unstable” (Augoyard 1991). The moving body of the flâneur, which can adapt to this changing space, seems to be in an ideal position to apprehend the metabolic body of the city. The flâneur is not only a “transparent eye-ball” (Emerson 2003), he is “a living eye” which communicates with all the other senses and captures the whole experience of moving through the city. By looking at texts by Balzac, Baudelaire, Dickens and Charlotte Brontë, the article shows that flânerie is a sensory activity that shapes our perception of the city as much as the city shapes our own flâneries by transforming our bodies into scribes who write the “thicks and thins of the urban text” (de Certeau, 1984).     

Exact calculation of power and sample size in bioequivalence studies using two one‐sided tests

The number of subjects in a pharmacokinetic two‐period two‐treatment crossover bioequivalence study is typically small, most often less than 60. The most common approach to testing for bioequivalence is the two one‐sided tests procedure. No explicit mathematical formula for the power function in the context of the two one‐sided tests procedure exists in the statistical literature, although the exact power based on Owen's special case of bivariate noncentral t‐distribution has been tabulated and graphed. Several approximations have previously been published for the probability of rejection in the two one‐sided tests procedure for crossover bioequivalence studies. These approximations and associated sample size formulas are reviewed in this article and compared for various parameter combinations with exact power formulas derived here, which are computed analytically as univariate integrals and which have been validated by Monte Carlo simulations. The exact formulas for power and sample size are shown to improve markedly in realistic parameter settings over the previous approximations. Copyright © 2014 John Wiley & Sons, Ltd.     

Letter to the editor by the authors of Exact Calculation of Power and Sample Size in Bioequivalence Studies Using Two One‐sided Tests,Pharmaceutical Statistics,DOI: 10.1002/pst.1666

This article reflects the views of the authors and should not be construed to be those of the US Food and Drug Administration. Copyright © 2015 John Wiley & Sons, Ltd.     

Providing better protection and promoting growth: A defence of Averting the old age crisis

This article briefly summarizes the recommendations of the recent World Bank report, Averting the old age crisis , analyses why representatives of the ISSA and the ILO came to quite different policy conclusions from that report, and takes up other selected issues. The article argues that there are four underlying reasons for the divergence between the World Bank and the ILO/ISSA positions: the Bank is more concerned about the impact of social security systems on the broader economy; the Bank is troubled by the inequities that we often find in current systems in practice, even though they may look equitable on paper; the Bank believes that behavioural responses and political economy factors sometimes make non-viable the design changes of public systems recommended by the ILO and the ISSA; and the Bank places considerable emphasis on the benefits of risk diversification.     

On a convergent stochastic estimation algorithm for frailty models

A maximum likelihood estimation procedure is presented for the frailty model. The procedure is based on a stochastic Expectation Maximization algorithm which converges quickly to the maximum likelihood estimate. The usual expectation step is replaced by a stochastic approximation of the complete log-likelihood using simulated values of unobserved frailties whereas the maximization step follows the same lines as those of the Expectation Maximization algorithm. The procedure allows to obtain at the same time estimations of the marginal likelihood and of the observed Fisher information matrix. Moreover, this stochastic Expectation Maximization algorithm requires less computation time. A wide variety of multivariate frailty models without any assumption on the covariance structure can be studied. To illustrate this procedure, a Gaussian frailty model with two frailty terms is introduced. The numerical results based on simulated data and on real bladder cancer data are more accurate than those obtained by using the Expectation Maximization Laplace algorithm and the Monte-Carlo Expectation Maximization one. Finally, since frailty models are used in many fields such as ecology, biology, economy, …, the proposed algorithm has a wide spectrum of applications.