1,720,962 research outputs found
Controlling for time-varying confounding in the longitudinal fixed effects model: A latent variable approach [Author Accepted Manuscript]
No full textFixed effects regression models are commonly used in longitudinal studies as a means to estimate causal effects while controlling for unobserved time-invariant confounders. But unobserved time-varying confounding remains potentially problematic, and identifying and measuring such confounders can be resource-intensive and costly. We propose a simple longitudinal model that builds on previous “common factor” models (Kenney 1975; Dormann 2001) and which can serve as a robustness check for the assumption of no unobserved time-varying confounding in the fixed effects approach. We posit a model with a latent autoregressive variable Zit, which represents the combined influence of both time-invariant and time-varying unobservables, and which is linked to the independent and dependent variables over time. Through Monte Carlo simulations and analyses of data from the Early Childhood Longitudinal Studies Kindergarten cohort (ECLS-K) and the Rural Substance Abuse and Violence Project (RSVP), we show that, under most conditions, the model provides less biased estimates than several variants of the traditional fixed-effects model. Our proposed approach offers applied researchers a practical check for gauging the extent to which the fixed effects assumption of no time-varying confounding may produce bias in the estimation of causal effects.reviewedacceptedVersio
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
Family Background, Cultural Capital, Obesity, and Academic Achievement in Childhood
No full textIn the dissertation, I attempt to show how and why students’ cultural knowledge and body shape are intertwined, which serve as an underlying mechanism of social and cultural reproduction in childhood. The dissertation consists of two main topics. For the first topic (second chapter), I investigate whether cultural capital matters for childhood obesity. While prior cultural capital studies have primarily focused on students’ affective and cognitive orientations to schooling, I focus on the possible link between cultural capital and obesity as an alternative explanation for reduced educational success among minority students. This study is the first to investigate the longitudinal effects of cultural capital on student body mass index with large scale data. For the second topic (third chapter), I attempt to identify the mediating mechanism in the relationship between childhood obesity and academic achievement. Despite the growing concern about weight stigmatization and discrimination in the US, no empirical studies have investigated possible mediating roles of teacher evaluation on obese children’s academic performance among marginalized subpopulations and have quantified the influence. To do so, I employ the newly released Early Childhood Longitudinal Study kindergarten cohort (ECLS-K: 2011), which is a nationally representative sample of American children who entered kindergarten in 2010-2011. In answering the proposed research questions, I attempt to exploit the advantages of structural equation modeling with a combination of econometric and quasi-experimental methods. The results of this study demonstrate that student cultural activity does reduce the risk of being obese in elementary schooling and that the negative influence of weight stigmatization might be comparable to racial discrimination or even more pronounced for minority girls. Taken together, this study shows us the nuanced ways in which educational and health inequalities are perpetuated or exacerbated in childhood
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
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