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  • Author or Editor: Bart Thijs x
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Abstract

The notion of ‘core documents’, first introduced in the context of co-citation analysis and later re-introduced for bibliographic coupling and extended to hybrid approaches, refers to the representation of the core of a document set according to given criteria. In the present study, core documents are used for the identification of new emerging topics. The proposed method proceeds from independent clustering of disciplines in different time windows. Cross-citations between core documents and clusters in different periods are used to detect new, exceptionally growing clusters or clusters with changing topics. Three paradigmatic types of new, emerging topics are distinguished. Methodology is illustrated using the example of four ISI subject categories selected from the life sciences, applied sciences and the social sciences.

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Abstract

The notion of ‘core documents’, first introduced in the context of co-citation analysis and later re-introduced for bibliographic coupling, refers to the representation of the core of a publication set according to given criteria. In the present study, the notion of core documents is extended to the combination of citation-based and textual links. It is shown that core documents defined this way can be used to represent and describe document clusters and topics at different levels of aggregation. Methodology is illustrated using the example of two ISI Subject Categories selected from applied and social sciences.

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In a recent paper the authors have studied the role of author self-citations within the process of documented scientific communication. Two important regularities such as the relative fast ageing of self-citations with respect to foreign citations and the “square-root law” characterising the conditional expectation of self-citations for given number of foreign citation have been found studying the phenomenon of author self-citations at the macro level. The goal of the present paper is to study the effect of author self-citations on macro indicators. The analysis of citation based indicators for 15 fields in the sciences, social sciences and humanities substantiates that at this level of aggregation there is no need for any revision of national indicators and the underlying journal citation measures in the context of excluding self-citations.

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Abstract  

In recent papers, the authors have studied basic regularities of author self-citations. The regularities are related to the ageing, to the relation between self-citations and foreign citations and to the interdependence of self-citations with other bibliometric indicators. The effect of multi-authorship on citation impact has been shown in other bibliometric studies, for instance, by Persson et al. (2004). The question arises whether those regularities imply any relation between number of co-authors and the extent of author self-citations. The results of the present paper confirm the common notion of such effects only in part. The authors show that at the macro level multi-authorship does not result in any exaggerate extent of self-citations.

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Abstract  

In the present study we propose a solution for a common problem in benchmarking tasks at institutional level. The usage of bibliometric indicators, even after standardisation, cannot disguise that comparing institutes remains often like comparing apples with pears. We developed a model to assign institutes to one of 8 different groups based on their research profile. Each group has a different focus: 1. Biology, 2. Agricultural Sciences, 3. Multidisciplinary, 4. Geo & Space Sciences, 5. Technical and natural Sciences, 6. Chemistry, 7. General and Research Medicine, 8. Specialised Medicine. Two applications of this methodology are described. In the first application we compare the composition of clusters at national level with the national research profiles. This gives a deeper insight in the national research landscape. In a second application we look at the dynamics of institutes by comparing their subject clustering at two different points in time.

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Summary  

In earlier studies by the authors, basic regularities of author self-citations have been analysed. These regularities are related to the ageing, to the relation between self-citations and foreign citations, to the interdependence of self-citations with other bibliometric indicators and to the influence of co-authorship on self-citation behaviour. Although both national and subject specific peculiarities influence the share of self-citations at the macro level, the authors came to the conclusion that - at this level of aggregation - there is practically no need for excluding self-citations. The aim of the present study is to answer the question in how far the influence of author self-citations on bibliometric meso-indicators deviates from that at the macro level, and to what extent national reference standards can be used in bibliometric meso analyses. In order to study the situation at the institutional level, a selection of twelve European universities representing different countries and different research profiles have been made. The results show a quite complex situation at the meso-level, therefore we suggest the usage of both indicators, including and excluding self-citations.

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Abstract  

The present study is part of an ongoing project on clustering European research institutions according to their publication profiles. Using hierarchical clustering eight clusters have been found the optimum solution for the classification. Aim of the present study is a structural analysis for the evaluation of research performance of specialised and multidisciplinary institutions. A breakdown by subject fields is used to characterise field-specific peculiarities of individual clusters by bibliometric indicators and to allow comparison within the same and among different clusters. Finally, benchmarks can then be used to study national research performance on basis of the institutional classification.

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The present paper analyses the role of author self-citations aiming at finding basic regularities of self-citations within the process of documented scientific communication and thus laying the methodological groundwork for a possible critical view at self-citation patterns in empirical studies at any level of aggregation. The study consists of three parts; the first part of the study is concerned with the comparative analysis of the ageing of self-citations and of non-self citations, in the second part the possible interdependence between self-citations and foreign citations is analysed and in the third part the interrelation of the share of self-citations in all citations with other citation-based indicators is studied. The outcomes of this study are two-fold; first, the results characterise author self-citations - at least at the macro level - as an organic part of the citation process obeying rules that can be measured and described with the help of mathematical models. Second, these rules can be used in evaluative micro and meso analyses to identify significant deviations from the reference standards.

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Abstract  

A bibliometric analysis of Spanish cardiovascular research is presented. The study focuses on the productivity, visibility and citation impact in an international, notably European context. Special attention is given to international collaboration. The underlying bibliographic data are collected from Thomson Reuters’s Web of Science on the basis of a ‘hybrid’ search strategy combining core journals, lexical terms and citation links especially developed for the field of cardiology.

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Abstract  

Based on data from the Science Citation Index Expanded (SCIE) and using scientometric methods, we conducted a systematic analysis of Chinese regional contributions and international collaboration in terms of scientific publications, publication activity, and citation impact. We found that regional contributions are highly skewed. The top positions measured by number of publications or citations, share of publications or citations are taken by almost the same set of regions. But this is not the case when indicators for relative citation impact are used. Comparison between regional scientific output and R&D expenditure shows that Spearman’s rank correlation coefficient between the two indicators is rather low among the leading publication regions.

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