1,720,957 research outputs found
Latent heterogeneity effects in modelling individual hazards: A non-proportional approach
No full textThis paper proposes an extension of individual hazard modelling through diffusion of innovation methodologies with the introduction of latent neighbouring effects in individual hazards. The proposal combines the Bemmaor's methodology for latent heterogeneous factors in the Cox proportional hazards model. The new model, the Bass-Bemmaor-Cox model, defines a non-proportional approach driven by a mixture of shifted Gompertz individual distributions where the time scale parameter governing growth dynamics depends upon observed covariates at the individual level. Conversely, individual propensity to the change of state included in the Gompertz sub-model is heterogeneous and latent within observed population. Based on experimental data referred to an ovarian pathology under treatment, an illustrative example is given. Further applications may be relevant for quantitative forecasting in marketing and technological diffusion contexts
Modelling dynamic market potential: Identifying hidden automata networks in the diffusion of pharmaceutical drugs
No full textThe dynamic market potential is nearly always a latent factor that drives the commercial performance of a product or service, namely, its diffusion. The modulation over time of a market potential may be grounded on the evolution of awareness of the product properties through a latent network among agents. This network may have different levels of connectivity, seeding effects and some type of heterogeneity of agents that affects their relationships. The GGM (Guseo and Guidolin (2009) [9]) introduces a specific evolutionary distribution for the market potential. This is based on the strong assumption of complete connectivity of the hidden network, supporting the growth of awareness focussed on specific pharmaceutical drugs or products with wide communication investments. Conversely, the basic idea proposed here is grounded on a convex combination of the Fibich–Gibori distribution, obtained for a minimally connected one-dimensional (1D) network topology, with the Bemmaor–Lee distribution, which takes into account unobserved heterogeneity aspects of agents in a market under a complete connectivity. Based on a continuum between opposite extremes, the extended final model, the Network Automata GGM (NA-GGM), which includes the GGM as a special case, allows the modulation of the involved latent network by exploiting the observed time series of sales and avoiding rigid assumptions on the latent network topology. A specific application of the new model is discussed in detail in term of the weekly diffusion of a statin, Rextat, in the central part of Italy. The proposed extension, NA-GGM, is statistically significant concerning the GGM and it is more coherent in commercial behaviour forecasting
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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