1,721,472 research outputs found
ACP Journal Club. Review: Routine venous thromboembolism prophylaxis in hospitalized frail older patients has uncertain benefit.
No full text[No abstract available]Kahn SR, 2012, CHEST, V141, pe195S; Qaseem A, 2011, ANN INTERN MED, V155, P625, DOI 10.7326-0003-4819-155-9-201111010-000110
Calculation of absolute risk for important outcomes in patients with and without a prognostic factor of interest
No full textBackground and Objectives: Primary studies and systematic reviews of prognostic factors commonly analyze and report relative measures of association between the factor(s) and outcome(s) of interest. For decision making, however, guideline panelists, systematic reviewers, and health care professionals at the point of care will ultimately need the absolute risk of the outcome(s) in those with and without the prognostic factor(s) of interest. The objective of the study was to develop a framework for calculating the absolute risk of the outcome(s) in those with and without the prognostic factor(s) of interest. Methods: We developed a mathematical approach to calculate the absolute risk of events from the relative measure of association, the total number of events and patients at risk, and the prevalence of the prognostic factor, all of which are usually reported in cohort studies assessing prognostic factors. We demonstrate how simpler approximations lead to biased estimates of absolute risk and thus the need for these formulas. We explain our logical framework using the simplest case, in which the measure of association is a relative risk, and provide extensions of the formula to odds ratios and hazard ratios. The same formulas can be applied to reports providing only the relative measure of association (e.g., case-control studies) by using external evidence regarding prevalence of the prognostic factor and overall risk of events. Conclusions: Our proposed formulas facilitate accurate calculation of measures of absolute risk in those with and without prognostic factors of interest for studies reporting the total number of events and patients at risk, the prevalence of the prognostic factor and a relative risk, odds ratio, or hazard ratio
How discriminating are discriminative instruments?
Full text linkThe McMaster framework introduced by Kirshner & Guyatt is the dominant paradigm for the development of measures of health status and health-related quality of life (HRQL). The framework defines the functions of such instruments as evaluative, predictive or discriminative. Evaluative instruments are required to be sensitive to change (responsiveness), but there is no corresponding index of the degree to which discriminative instruments are sensitive to cross-sectional differences.This paper argues that indices of validity and reliability are not sufficient to demonstrate that a discriminative instrument performs its function of discriminating between individuals, and that the McMaster framework would be augmented by the addition of a separate index of discrimination. The coefficient proposed by Ferguson (Delta) is easily adapted to HRQL instruments and is a direct, non-parametric index of the degree to which an instrument distinguishes between individuals. While Delta should prove useful in the development and evaluation of discriminative instruments, further research is required to elucidate the relationship between the measurement properties of discrimination, reliability and responsivenes
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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