Image‐Based Empirical Importance Sampling: An Efficient Way of Estimating Intensities

Abstract. Very recently, it has been suggested in the biomedical literature to combine computerized image analysis with non‐uniform sampling to increase the efficiency of estimators of intensities of biological cell populations. We give this ingenious idea of empirical importance sampling a stochastic formulation, using point process theory and modern sampling theory. We develop statistical tools for assessing its efficiency and construct optimal model‐based estimators of intensities. Examples of applications of empirical importance sampling in microscopy are provided.     

AN ESTIMATE OF THE AGE DISTRIBUTION'S EFFECT ON CARBON DIOXIDE EMISSIONS

We estimate the age distribution's impact on carbon dioxide emissions from 1990 to 2006 by exploiting demographic variation in a panel of 46 countries. To eliminate potential bias from endogeneity or omitted variables, we instrument for the age distribution in a country's current population with lagged birth rates, and the regressions control for total population, total output, and country and year fixed effects. Carbon dioxide emissions increase with the share of the population aged 35 to 49 years, and this result is statistically significant and quantitatively large. (JEL Q4, J1)     

The Abduction of Credibility: A Reply to John Paley

Correspondence to Liz Kelly, Child and Woman Abuse Studies Unit, Ladbroke House, 62-66 Highbury Grove, London, N5 2AD Summary This response takes issue with John Paley's paper ‘SatanistAbuse and Alien Abduction’ (this issue) in a number ofareas: his definition of Satanic ritual abuse (SRA); the parallelshe draws between SRA and alien abduction; his assertions thatthere is no evidence of SRA and that accounts of SRA can beviewed as urban legends; and his ‘temporal lobe connection’conclusion.     

The Social Worker, the Client and the Social Anthropologist

Summary City Centre Project has been working with drifting and homelessyoung people and we considered it important to study not justthe clients, but also the project workers. The discipline andmethods of social anthropology appeared to offer unique advantagesin this attempt However, in the course of our fieldwork, weencountered situations which led us to question the validityof using participant observation with clients, and to explorethe tensions between social workers and academic researchers.We then altered our methods for gathering data, and realizedthat our experience had important implications for researchersconsidering the use of qualitative methods in a social worksetting. This article is our first attempt to generalize fromour particular experience, and to raise questions about powerrelations among the parties to research and action.     

Alternative estimates of the volume of emigration from Canada, 1961–71*

L'apport de l'immigration à l'accroissement de la population au Canada a souvent fait l'objet d'une attention toute particulière. Cependant, on est beaucoup moins bien renseigné sur l'impact qu'a pu avoir l'émigration, puisqu'il n'existe aucune donnée sur le nombre réel de personnes quittant le Canada. Cet exposé présente d'abord trois évaluations du nombre d'émigrants du Canada au cours de la période intercensitaire 1961–71, obtenues à partir de trois méthodes différentes, et on tente de déterminer quelle évaluation est la plus fiable. On montre que le processus d'élaboration des politiques canadiennes d'immigration se doit de tenir compte de l'émigration. The contribution of immigration to Canada's population growth has received considerable analytical attention. However, much less is known about the impact which emigration has had on the nation's population growth, particularly since actual data are not available on the number of persons emigrating from Canada. This paper presents three different emigration estimates for Canada for the 1961–71 intercensal period derived from different estimation procedures, endeavours to determine which estimate is the most reliable one, and demonstrates the importance of considering emigration in the continuing reformulation of Canada's immigration policies.     

Lévy‐based Modelling in Brain Imaging

Abstract. A substantive problem in neuroscience is the lack of valid statistical methods for non‐Gaussian random fields. In the present study, we develop a flexible, yet tractable model for a random field based on kernel smoothing of a so‐called Lévy basis. The resulting field may be Gaussian, but there are many other possibilities, including random fields based on Gamma, inverse Gaussian and normal inverse Gaussian (NIG) Lévy bases. It is easy to estimate the parameters of the model and accordingly to assess by simulation the quantiles of test statistics commonly used in neuroscience. We give a concrete example of magnetic resonance imaging scans that are non‐Gaussian. For these data, simulations under the fitted models show that traditional methods based on Gaussian random field theory may leave small, but significant changes in signal level undetected, while these changes are detectable under a non‐Gaussian Lévy model.