1,720,969 research outputs found
On the Asymptotic Behaviour of Random Cumulative Hazards
No full textCentral limit theorems for functionals of random hazard rates provide a synthetic picture of the global shape of a given hazard rate model. It has been shown that, for the most popular mixture hazard models with completely random mixing measures, the long-term trend and asymptotic variance of the cumulative hazard are not affected by conditioning on observations, so that the behavior of the posterior for large time horizons is systematically determined by the prior choice. In this paper we derive Berry-Ess\'een bounds for prior and posterior CLTs by using a recent technique based on Stein's method for normal approximation of Poisson functionals. The general result is specialized to various specific kernels and it shows that the data enters the second leading term of the prior bound by increasing it
An asymptotic analysis of a class of discrete nonparametric priors
Full text linkIn this paper we analyze the asymptotic behaviour of a large class of nonparametric priors, namely Gibbs-type priors, which represent a natural generalization of the Dirichlet process. After determining their topological support, we specifically investigate consistency of such priors according to the "what if", or frequentist, approach, which postulates the existence of a "true" distribution . We provide a full taxonomy of their limiting behaviours: consistency holds essentially always for discrete , whereas inconsistency may occur for diffuse . Such findings are further illustrated by means of three specific priors admitting closed form expressions and exhibiting a wide range of asymptotic behaviours. For both Gibbs-type priors and discrete nonparametric priors in general, the possible inconsistency should not be interpreted as evidence against their use "tout court". It rather represents an indication that they are designed for modeling discrete distributions, at which consistency holds true, and a neat evidence against their use in the case of diffuse
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
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
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