1,721,102 research outputs found
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
Longitudinal analysis of the health-related quality of life in oncology
No full textLa qualité de vie relative à la santé (QdV) est désormais un des objectifs majeurs des essais cliniques en cancérologie pour pouvoir s’assurer du bénéfice clinique de nouvelles stratégies thérapeutiques pour le patient. Cependant, les résultats des données de QdV restent encore peu pris en compte en pratique clinique en raison de la nature subjective et dynamique de la QdV. De plus, les méthodes statistiques pour son analyse longitudinale doivent être capables de tenir compte de l’occurrence des données manquantes et d’un potentiel effet Response Shift reflétant l’adaptation du patient vis-à-vis de la maladie et de la toxicité du traitement. Ces méthodes doivent enfin proposer des résultats facilement compréhensibles par les cliniciens.Dans cette optique, les objectifs de ce travail ont été de faire le point sur ces facteurs limitants et de proposer des méthodes adéquates pour une interprétation robuste des données de QdV longitudinales. Ces travaux sont centrés sur la méthode du temps jusqu’à détérioration d’un score de QdV (TJD), en tant que modalité d’analyse longitudinale, ainsi que sur la caractérisation de l’occurrence de l’effet Response Shift.Les travaux menés ont donné lieu à la création d’un package R pour l’analyse longitudinale de la QdV selon la méthode du TJD avec une interface facile d’utilisation. Certaines recommandations ont été proposées sur les définitions de TJD à appliquer selon les situations thérapeutiques et l’occurrence ou non d’un effet Response Shift. Cette méthode attractive pour les cliniciens a été appliquée dans le cadre de deux essais de phase précoces I et IL La méthode de pondération par probabilité inversée du score de propension a été investiguée conjointement avec la méthode du TJD afin de tenir compte de l’occurrence de données manquantes dépendant des caractéristiques des patients. Une comparaison de trois approches statistiques pour l’analyse longitudinale a montré la performance du modèle linéaire mixte et permet de donner quelques recommandations pour l’analyse longitudinale selon le design de l’étude. Cette étude a également montré l’impact de l’occurrence de données manquantes informatives sur les méthodes d’analyse longitudinale. Des analyses factorielles et modèles issus de la théorie de réponse à l’item ont montré leur capacité à caractériser la Response Shift conjointement avec la méthode Then-test. Enfin, bien que les modèles à équation structurelles soient régulièrement appliqués pour caractériser cet effet sur le questionnaire de QdV générique SF-36, ils semblent peu adaptés à la structure des questionnaires spécifiques du cancer du groupe « European Organization of Research and Treatment of Cancer » (EORTCHealth-related quality of life (HRQoL) has become one of the major objectives of oncology clinical trials to ensure the clinical benefit of new treatment strategies for the patient. However, the results of HRQoL data remain poorly used in clinical practice due to the subjective and dynamic nature of HRQoL. Moreover, statistical methods for its longitudinal analysis hâve to take into account the occurrence of missing data and the potential Response Shift effect reflecting patient’s adaptation of the disease and treatment toxicities. Finally, these methods should also propose some results easy understandable for clinicians.In this context, this work aimed to review these limiting factors and to propose some suitable methods for a robust interprétation of longitudinal HRQoL data. This work is focused on both the Time to HRQoL score détérioration (TTD) as a modality of longitudinal analysis and the characterization of the occurrence of the Response Shift effect.This work has resulted in the création of an R package for the longitudinal HRQoL analysis according to the TTD with an easy to use interface. Some recommendations were proposed on the définitions of the TTD to apply according to the therapeutic settings and the potential occurrence of the Response Shift effect. This attractive method was applied in two early stage I and II trials. The inverse probability weighting method of the propensity score was investigated in conjunction with the TTD method to take into account the occurrence of missing data depending on patients’ characteristics. A comparison between three statistical approaches for the longitudinal analysis showed the performance of the linear mixed model and allows to give some recommendations for the longitudinal analysis according to the study design. This study also highlighted the impact of the occurrence of informative missing data on the longitudinal statistical methods. Factor analyses and Item Response Theory models showed their ability to characterize the occurrence of the Response Shift in conjunction with the Then- test method. Finally, although the structural équations modeling are often used to characterize this effect on the SF-36 generic questionnaire, they seem not appropriated to the particular structure of the HRQoL cancer spécifie questionnaires of the European Organization of Research and Treatment of Cancer (EORTC) HRQoL grou
Joint models for the longitudinal analysis of the health-related quality of life in presence of informative dropouts in oncology
No full textLa qualité de vie relative à la santé (QdV) est de plus en plus utilisée comme critère de jugement dans les essais cliniques en oncologie. Elle est évaluée par le biais d’auto-questionnaires transmis aux patients à différentes visites au cours de leur prise en charge. Cependant, ces questionnaires sont souvent en partie incomplets, voire complètement manquants ; en particulier, chez les patients en situation palliative où les questionnaires non remplis pourraient être le résultat d’une progression de la maladie ou d’un décès. Les modèles linéaires mixtes (LMMs) sont habituellement utilisés pour l’analyse longitudinale de la QdV, mais peuvent donner des estimations biaisées en présence de données manquantes informatives, i.e. si le mécanisme de données manquantes est lié aux données manquantes de QdV. L’objectif de ce travail a été d’étudier différentes stratégies pour analyser les données longitudinales de QdV tout en tenant compte des sorties d’étude informatives. Dans l’ensemble du manuscrit, les modèles ont été illustrés sur les données de l’essai clinique PRODIGE 5/ACCORD 17, qui a inclus 267 patients atteints d’un cancer de l’œsophage avancé.D’abord, trois modèles – le modèle de sélection (SM), le modèle de mélange de profils (PMM) et le modèle à effets partagés (SPM) – ont été étudiés. Le SPM (ou modèle conjoint), composé d’un sous-modèle pour les trajectoires de QdV (LMM) associé à un sous-modèle pour le temps jusqu’à sortie d’étude (modèle de survie), semble être l’approche la plus intéressante aussi bien d’un point de vue théorique que pratique. Ensuite, nous avons étudié l’intérêt de considérer un sous-modèle à risques concurrents pour le temps jusqu’à sortie d’étude, afin d’analyser l’évolution de la QdV en présence de deux causes de sortie d’étude. La comparaison d’un modèle conjoint standard par rapport à un modèle conjoint à risques concurrents a été réalisée en considérant plusieurs scénarios au travers d’une étude de simulations. Nous avons montré que le modèle conjoint à risques concurrents pouvait être utile pour faire la distinction entre des sorties d’étude informatives et non informatives. Enfin, nous avons envisagé d’autres modélisations du sous-modèle pour les trajectoires des scores de QdV plus adaptées aux spécificités associées aux données de score de QdV. Nous avons utilisé des splines pour modéliser des trajectoires non linéaires de QdV, et des modèles linéaires mixtes généralisés (GLMMs), pour considérer le score de QdV en tant que variable ordinale.The use of health-related quality of life (HRQoL) as an endpoint in cancer clinical trials is growing rapidly. HRQoL is assessed at different visit times throughout the care process by self-administered questionnaires. However, these questionnaires are frequently incomplete (partially or entirely), and, among patients in palliative care, this could unfortunately be the consequence of dropouts related to disease progression or death. Linear mixed models (LMMs) are generally used to analyze longitudinal data of HRQoL, but they are likely to produce biased estimates in the presence of informative missing data, i.e., if missingness is correlated with the missing HRQoL outcome. The objective of this work was to study modeling alternatives to analyze longitudinal data of HRQoL while accounting for informative dropouts. Throughout the manuscript, all the models were illustrated on the clinical trial PRODIGE 5/ACCORD 17 including 267 patients with advanced esophageal cancer. First, three statistical models – the selection model (SM), the pattern-mixture model (PMM), and the shared-parameters model (SPM) – were investigated. The SPM, or joint model, which is composed of a sub-model for the HRQoL trajectory (LMM) linked with a sub-model for the time-to-dropout (survival model), appeared to be the most interesting from both theoretical and practical viewpoints. Then, we studied the interest of using a competing risks sub-model for the time-to-dropout to analyze HRQoL longitudinal data in the presence of two causes of dropout. The impact of using a standard instead of a competing risks joint model in various situations was investigated in a simulation study. We showed that the competing risks joint model could be useful to distinguish between informative and non-informative dropouts. Finally, we explored how the sub-model for the HRQoL score trajectory could be more adapted to the specificities of the HRQoL score data. We used splines to fit nonlinear trajectories and consider generalized linear mixed models (GLMMs) to treat the HRQoL score as an ordinal variable
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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