1,720,968 research outputs found
Population size estimation via alternative parametrizations for Poisson mixture models
Full text linkWe exploit a suitable moment-based reparametrization of the Poisson mixtures distributions for developing classical and Bayesian inference for the unknown size of a finite population in the presence of count data. Here we put particular emphasis on suitable mappings between ordinary moments and recurrence coefficients that will allow us to implement standard maximization routines and MCMC routines in a more convenient parameter space. We assess the comparative performance of our approach in real data applications and in a simulation study
From National Indicators to environmental sustainability indices: new challenges
No full textThe need of meaningful environmental sustainability indexes for international comparisons is nowadays commonly perceived: the production of comparable national indicators by Eurostat has been enhanced in the most recent years. Such national indicators, as a primary desiderata, should not be in contrast with the – usually more detailed - information provided by other indicators calculated at various sub-national levels. The gist of our paper is to discuss the role of statistics in the production of reliable indicators of environmental sustainability, based on survey and administrative data provided by national and international agencies. Ideally, the statistician should find his/her place in between data release and the economist in order to highlight potentially important and useful relations between environmental and economical indicators. For example one could be very interested in detecting the presence of spatial (or spatio-temporal) clustering of countries in terms of the indicators. In this paper we will mainly focus on descriptive indexes: starting from the Eurostat production of official environmental indicators we will try to discuss the main issues which may arise when those indexes are used in policy making
Ditelo con un grafico
No full textWe liive a world of data. Almost every human activity is nowadays "measured" in a way or another. In this paper we briefly review the most popular ways in which statistical infomation can be represented in a graphical wa
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
A Component Multiplicative Error Model for Realized Volatility Measures
No full textWe propose a component Multiplicative Error Model (MEM) for modelling and forecasting realized volatility measures. In contrast to conventional MEMs, the proposed specification resorts to the use of a multiplicative component structure in order to parsimoniously parameterize the complex dependence structure of realized volatility measures. The long-run component is defined as a linear combination of MIDAS filters moving at different frequencies, while the short-run component is constrained to follow a unit mean GARCH recursion. This particular specification of the long-run component allows to reproduce very persistent oscillations of the conditional mean of the volatility process, in the spirit of Corsi's Heterogeneous Autoregressive Model (HAR). The empirical performances of the proposed model are assessed by means of an application to the realized volatility of the S&P 500 index
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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