1,722,348 research outputs found
Components of change in repeated surveys
No full textProposals are made for decomposing net change of population means and totals through time into components which are interpretable and lead to a better understanding of net change. The framework is extended to allow for non-stationary populations with births, deaths and changing characteristics of continuing members. Design and estimation issues are investigated and a number of numerical examples given. /// Nous proposons une methode pour decomposer les changements nets au cours du temps des moyennes et des tailles de population, en composantes qui ont une interpretation et qui menant a une meilleure comprehension des changements nets. Cette approche est generalisee afin de permettre l'etude de populations nonstationaires avec naissances et morts, dont les survivants ont des characteristiques variables. Le probleme du plan de sondage et celui de l'estimation sont etudies et plusieurs exemples numeriques sont donnes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Multiple frame sampling for multivariate stratification
No full textA sampling design is considered for multipurpose surveys in which several stratifying variables are available and the objective is to estimate totals or means of several variables, each highly correlated with one of the stratifying variables. The design involves selecting separate subsamples independently by stratified sampling with respect to each of the stratifying variables in turn. Estimation then involves pooling data from the separate subsamples using methods from multiple frame sampling. The strategy is compared with standard approaches in a simulation study and it is shown that significant gains in efficiency can arise. The application of the proposed strategy to a market research problem of designing a survey of readership of agricultural publications is described.Nous proposons un nouveau plan de sondage pour des enquetes ou plusieurs de variables de stratification sont disponible et le but est l'estimation des totaux et des moyennes de plusieurs de variables, chaqu'une correlee fortement avec une des variables de stratification. Le plan d'echantillon se compose de la selection de plusieurs d'echantillons independants selon echantillonage stratifie par chaque variable de stratification tour a tour. Pour l'estimation on combine les donnees des echantillons independants par les techniques qui sont utilises dans les enquetes avec quelques bas de sondages. Une etude par simulation compare le nouvel plan et les plans conventionaux et nous trouvous que le gain d'efficience du nouvel plan peut etre grand. L'application du plan propose au dessein d'une enquete des lecteurs des publications agricoles est decrite
The effect of two-stage sampling on the F-statistic
No full textThe assumption of iid observations that underlies many statistical procedures is called into question when analyzing complex survey data. The population structure-particularly the existence of clusters in two-stage samples that usually exhibit positive intracluster correlation-invalidates the independence assumption. Kish and Frankel (1974) investigated the impact of this fact on regression analysis by using the standard sample-survey-theory framework; Campbell (1977) and Scott and Holt (1982) used the linear model framework. In general, although ordinary least squares (OLS) procedures are unbiased but not fully efficient for estimation of the regression coefficients, serious difficulties can arise when using OLS estimators for second-order terms. Variances of the OLS estimators for the regression coefficients can be larger (sometimes much larger) than the usual OLS variance expression would indicate. Failure to consider this possibility leads to underestimation of variances, with consequences for confidence intervals. This article follows this effect through to the F statistic, because of its importance to hypothesis tests and confidence ellipsoids. Our major aim is to investigate the effect of intracluster correlation on the F statistic. We propose a diagnostic measure identifying when the ordinary F statistic is likely to be affected and give decomposition in terms of the contributions of the individual regressors and their cross-products, based on a similar decomposition for the projection matrix in Appendix A. We establish numerically and theoretically the effectiveness of this measure in understanding the degree of distortion of F by intracluster correlation. The measure leads to a correction for the F test for unknown intracluster correlation. This is a slightly simpler numerical procedure than the generalized least squares (GLS), since it does not require iteration. The correction is shown to perform at least as well as the GLS in a simulation study
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