1,721,038 research outputs found
Incident disability in older adults: prediction models based on two British prospective cohort studies
No full textObjective: to develop and validate a prediction model for incident locomotor disability after 7 years in older adults.Setting: prospective British cohort studies: British Women's Heart and Health Study (BWHHS) for development and the English Longitudinal Study of Ageing (ELSA) for validation.Subjects: community-dwelling older adults.Methods: multivariable logistic regression models after selection of predictors with backward elimination. Model performance was assessed using metrics of discrimination and calibration. Models were internally and externally validated.Results: locomotor disability was reported in BWHHS by 861 of 1,786 (48%) women after 7 years. Age, a history of arthritis and low physical activity levels were the most important predictors of locomotor disability. Models using routine measures as predictors had satisfactory calibration and discrimination (c-index 0.73). Addition of 31 blood markers did not increase the predictive performance. External validation in ELSA showed reduced discrimination (c-index 0.65) and an underestimation of disability risks. A web-based calculator for locomotor disability is available (http://www.sealedenvelope.com/trials/bwhhsmodel/).Conclusions: we developed and externally validated a prediction model for incident locomotor disability in older adults based on routine measures available to general practitioners, patients and public health workers, and showed an adequate discrimination. Addition of blood markers from major biological pathways did not improve the performance of the model. Further replication in additional data sets may lead to further enhancement of the current model
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
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
Challenges of studying and predicting chronic kidney disease progression and its complications using routinely collected electronic healthcare records
Full text linkChronic kidney disease (CKD) affects over 10% of the population worldwide. Complications include cardiovascular morbidity, death, and progression to kidney failure requiring dialysis. The number of CKD cases is growing, with implications for patients and healthcare services. Action is needed to support earlier diagnosis and better targeted care with the potential to delay disease progression and reduce associated complications. Increasing availability of electronic healthcare records (EHRs) can support study of CKD and its progression in the general population. Regular kidney function testing which is recommended in clinical practice has the potential to capture patients with CKD and subsequent progression of disease. Large sample sizes and long duration of follow-up can support study of rare outcomes such as kidney failure and decline in kidney function which may progress slowly over many years in some patients. However, there is variation in recognition of CKD in clinical practice and there are challenges in detecting CKD due to its asymptomatic nature in the early stages, relying on blood tests to detect. Availability of kidney function test results is likely to depend on patient risk factors, healthcare seeking behaviours and healthcare provider factors (“informative testing”). This may lead to selection bias and impact reliability of research findings. This thesis aimed to explore and highlight the challenges resulting from issues of data quality and completeness inherent to EHRs when used to study the epidemiology of progression of CKD, and to present approaches to overcome these challenges. Firstly, a systematic review showed substantial risks of selection bias in previous research, due to selection procedures for study inclusion and completeness of data captured during follow-up for outcomes. Generally, large proportions of patients were excluded from analysis due to missing data, with little reflection on the implications of bias in study results and unrepresentative samples. Statistical methodology varied widely, with varying capability of handling missing data. Secondly, a feasibility study investigated data quality and completeness for kidney function tests conducted in UK primary care. Testing was uncommon in adults overall, but there was high frequency of repeat testing in patients with risk factors for CKD, with the potential to capture most patients with CKD. However, reasons for missing data weren’t clear, and data may be disproportionately missing due to certain risk factors or management in secondary care. Data quality issues due to historical laboratory reporting problems led to underestimation of decline in kidney function but impact was small in most patients. Thirdly, we studied the association between GP practice completeness of diagnostic coding for CKD and patient-level hospitalisation outcomes in patients with CKD in England. The use of a practice-level exposure aimed to reduce risks of unmeasured confounding. Being registered at a higher coding practice was associated with lower rates of hospitalisations for CV events, after adjustment for other practice factors. Finally, we developed new risk prediction equations for kidney failure requiring dialysis, using EHRs capturing the entire healthcare system in Stockholm, Sweden. Previously validated equations require data that is not routinely collected in most patients, but our analysis included 98% of patients identified with CKD, by including predictor variables that are routinely available. New models were precisely estimated and achieved high discrimination. EHRs hold huge value to study progression of CKD due to large sample size and long duration of regularly collected kidney function tests. However, issues of informative missingness and sampling bias have not been appropriately acknowledged and addressed in previous research. Future research should ensure that research questions can be answered with available data using appropriate statistical techniques, and with improved transparency of potential for selection bias. Research in this thesis has strengthened evidence for the importance of diagnostic coding for CKD in clinical practice in reducing risk of complications of CKD, by enabling improved patient care. New risk models have the potential to improve equality of healthcare, enabling risk prediction in all patients with CKD, but require validation in the UK
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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