1,721,221 research outputs found
Evaluation of diagnostic tests when there is no gold standard. A review of methods
Full text linkOBJECTIVE: To generate a classification of methods to evaluate medical tests when
there is no gold standard.
METHODS: Multiple search strategies were employed to obtain an overview of the
different methods described in the literature, including searches of electronic
databases, contacting experts for papers in personal archives, exploring
databases from previous methodological projects and cross-checking of reference
lists of useful papers already identified.
RESULTS: All methods available were classified into four main groups. The first
method group, impute or adjust for missing data on reference standard, needs
careful attention to the pattern and fraction of missing values. The second
group, correct imperfect reference standard, can be useful if there is reliable
information about the degree of imperfection of the reference standard and about
the correlation of the errors between the index test and the reference standard.
The third group of methods, construct reference standard, have in common that
they combine multiple test results to construct a reference standard outcome
including deterministic predefined rules, consensus procedures and statistical
modelling (latent class analysis). In the final group, validate index test
results, the diagnostic test accuracy paradigm is abandoned and research
examines, using a number of different methods, whether the results of an index
test are meaningful in practice, for example by relating index test results to
relevant other clinical characteristics and future clinical events.
CONCLUSIONS: The majority of methods try to impute, adjust or construct a
reference standard in an effort to obtain the familiar diagnostic accuracy
statistics, such as sensitivity and specificity. In situations that deviate only
marginally from the classical diagnostic accuracy paradigm, these are valuable
methods. However, in situations where an acceptable reference standard does not
exist, applying the concept of clinical test validation can provide a significant
methodological advance. All methods summarised in this report need further
development. Some methods, such as the construction of a reference standard using
panel consensus methods and validation of tests outwith the accuracy paradigm,
are particularly promising but are lacking in methodological research. These
methods deserve particular attention in future research
Statistical methods for investigating heterogeneity related to methodological quality in meta-analyses of studies of diagnostic accuracy [Oral O28]
No full text
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
- …
