| 1. |
- Ahlgren, Per, et al.
(författare)
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Community Detection Using Citation Relations and Textual Similarities in a Large Set of PubMed Publications
- 2019
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Ingår i: PROCEEDINGS OF THE 17th INTERNATIONAL CONFERENCE ON SCIENTOMETRICS & INFORMETRICS. - Leuven : International Society for Scientometrics and Informetrics. - 9788833811185 ; , s. 1380-1392
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Konferensbidrag (refereegranskat)abstract
- In this contribution, the effects of enhancing direct citations, with respect to publication-publication relatedness measurement, by indirect citation relations (bibliographic coupling and co-citation) and text relations on clustering accuracy are analyzed. In total, we investigate six approaches. In one of these, direct citations are enhanced by both bibliographic coupling and co-citation, whereas text relations are used to enhance direct citations in another approach. In addition to an approach based on direct citations only, we include in the study, for comparison reasons, each approach that is involved in the enhancement of direct citations. For the evaluation of the approaches, we use a methodology proposed by earlier research. However, the used evaluation criterion is based on MeSH, arguable the most sophisticated item-level classification scheme available. The results show that the co-citation approach has the worst performance, and that the direct citations approach is outperformed by the other four investigated approaches. An approach in which direct citations are enhanced by the BM25 textual relatedness measure has the best performance, followed by the approach that combines direct citations with bibliographic coupling and co-citation. The latter performs slightly better than the bibliographic coupling approach, which in turn has a better performance than the BM25 approach.
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| 2. |
- Ahlgren, Per, 1960-, et al.
(författare)
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Document-document similarity approaches and science mapping: experimental comparison of five approaches
- 2009
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Ingår i: Journal of Informetrics. - Netherlands : Elsevier BV. - 1751-1577 .- 1875-5879. ; 3:1, s. 49-63
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Tidskriftsartikel (refereegranskat)abstract
- This paper treats document–document similarity approaches in the context of science mapping. Five approaches, involving nine methods, are compared experimentally. We compare text-based approaches, the citation-based bibliographic coupling approach, and approaches that combine text-based approaches and bibliographic coupling. Forty-three articles, published in the journal Information Retrieval, are used as test documents. We investigate how well the approaches agree with a ground truth subject classification of the test documents, when the complete linkage method is used, and under two types of similarities, first-order and second-order. The results show that it is possible to achieve a very good approximation of the classification by means of automatic grouping of articles. One text-only method and one combination method, under second-order similarities in both cases, give rise to cluster solutions that to a large extent agree with the classification.
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| 3. |
- Ahlgren, Per, et al.
(författare)
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Enhancing direct citations : A comparison of relatedness measures for community detection in a large set of PubMed publications
- 2020
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Ingår i: Quantitative Science Studies. - : MIT Press - Journals. - 2641-3337. ; 1:2, s. 714-729
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Tidskriftsartikel (refereegranskat)abstract
- The effects of enhancing direct citations, with respect to publication–publication relatednessmeasurement, by indirect citation relations (bibliographic coupling, cocitation, and extendeddirect citations) and text relations on clustering solution accuracy are analyzed. Forcomparison, we include each approach that is involved in the enhancement of direct citations.In total, we investigate the relative performance of seven approaches. To evaluate theapproaches we use a methodology proposed by earlier research. However, the evaluationcriterion used is based on MeSH, one of the most sophisticated publication-level classificationschemes available. We also introduce an approach, based on interpolated accuracy values,by which overall relative clustering solution accuracy can be studied. The results show thatthe cocitation approach has the worst performance, and that the direct citations approach isoutperformed by the other five investigated approaches. The extended direct citations approachhas the best performance, followed by an approach in which direct citations are enhancedby the BM25 textual relatedness measure. An approach that combines direct citations withbibliographic coupling and cocitation performs slightly better than the bibliographic couplingapproach, which in turn has a better performance than the BM25 approach.
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| 4. |
- Ahlgren, Per, et al.
(författare)
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Exploring the relation between referencing practices and citation impact : A large-scale study based on Web of Science data
- 2018
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Ingår i: Journal of the Association for Information Science and Technology. - : John Wiley & Sons. - 2330-1635 .- 2330-1643. ; 69:5, s. 728-743
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Tidskriftsartikel (refereegranskat)abstract
- In this large-scale contribution, we deal with the relationship between properties of cited references of Web of Science articles and the field normalized citation rate of these articles. Using nearly 1 million articles, and three classification systems with different levels of granularity, we study the effects of number of cited references, share of references covered by Web of Science, mean age of references and mean citation rate of references on field normalized citation rate. To expose the relationship between the predictor variables and the response variable, we use quantile regression. We found that a higher number of references, a higher share of references to publications within Web of Science and references to more recent publications correlate with citation impact. A correlation was observed even when normalization was done with a finely grained classification system. The predictor variables affected citation impact to a larger extent at higher quantile levels. Regarding the relative importance of the predictor variables, citation impact of the cited references was in general the least important variable. Number of cited references carried most of the importance for both low and medium quantile levels, but this importance was lessened at the highest considered level.
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| 5. |
- Ahlgren, Per, et al.
(författare)
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Field normalized citation rates, field normalized journal impact and Norwegian weights for allocation of university research funds
- 2012
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Ingår i: Scientometrics. - : Springer. - 0138-9130 .- 1588-2861. ; 92:2, s. 767-780
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Tidskriftsartikel (refereegranskat)abstract
- We compared three different bibliometric evaluation approaches: two citationbased approaches and one based on manual classification of publishing channels into quality levels. Publication data for two universities was used, and we worked with two levels of analysis: article and department. For the article level, we investigated the predictive power of field normalized citation rates and field normalized journal impact with respect to journal level. The results for the article level show that evaluation of journals based on citation impact correlate rather well with manual classification of journals into quality levels. However, the prediction from field normalized citation rates to journal level was only marginally better than random guessing. At the department level, we studied three different indicators in the context of research fund allocation within universities and the extent to which the three indicators produce different distributions of research funds. It turned out that the three distributions of relative indicator values were very similar, which in turn yields that the corresponding distributions of hypothetical research funds would be very similar.
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| 6. |
- Ahlgren, Per, et al.
(författare)
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Textual content, cited references, similarity order, and clustering : an experimental study in the context of science mapping
- 2009
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Ingår i: Proceedings of the 12th International Conference on Scientometrics and Informetrics. ; , s. 862-873
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Konferensbidrag (refereegranskat)abstract
- This paper deals with document-document similarity approaches, the issue of similarity order, and clustering methods, in the context of science mapping. Using two data sets of bibliographic records, associated with the fields of information retrieval and scientometrics, we investigate how well two document-document similarity approaches, a text-based approach and bibliographic coupling, agree with ground truth classifications (obtained by subject experts), under first-order and second-order similarities, and under four different clustering methods. The clustering methods are average linkage, complete linkage, Ward’s method and consensus clustering. The performance of first-order and second-order similarities is compared within the two document-document similarity approaches, and under each clustering method. We also compare the performance of the clustering methods. The results show that the text-based approach consistently outperformed bibliographic coupling with regard to the information retrieval data set, but performed consistently worse than the latter approach regarding the scientometrics data set. For the similarity order issue, second-order similarities performed better than first-order in 12 out of 16 cases. Average linkage had the best overall performance among the clustering methods, followed by consensus clustering. The main conclusion of the study is that second-order similarities seem to be a better choice than first-order in the science mapping context.
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| 7. |
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| 8. |
- Aksnes, Dag W., et al.
(författare)
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Arctic Research Trends : Bibliometrics 2016-2022
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This work was conducted by the UArctic Thematic Network on Research Analytics and Bibliometrics. It was supported by Global Affairs Canada through the Global Arctic Leadership Initiative.
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| 9. |
- Colliander, Cristian, 1980-
(författare)
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A novel approach to citation normalization : a similarity-based method for creating reference sets
- 2015
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Ingår i: Journal of the Association for Information Science and Technology. - : Wiley-Blackwell. - 2330-1635 .- 2330-1643. ; 66:3, s. 489-500
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Tidskriftsartikel (refereegranskat)abstract
- A similarity-oriented approach for deriving reference values used in citation normalization is explored and contrasted with the dominant approach of utilizing database-defined journal sets as a basis for deriving such values. In the similarity-oriented approach, an assessed article's raw citation count is compared with a reference value that is derived from a reference set, which is constructed in such a way that articles in this set are estimated to address a subject matter similar to that of the assessed article. This estimation is based on second-order similarity and utilizes a combination of 2 feature sets: bibliographic references and technical terminology. The contribution of an article in a given reference set to the reference value is dependent on its degree of similarity to the assessed article. It is shown that reference values calculated by the similarity-oriented approach are considerably better at predicting the assessed articles' citation count compared to the reference values given by the journal-set approach, thus significantly reducing the variability in the observed citation distribution that stems from the variability in the articles' addressed subject matter.
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| 10. |
- Colliander, Cristian, 1980-, et al.
(författare)
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Comparison of publication-level approaches to ex-post citation normalization
- 2019
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Ingår i: Scientometrics. - : SPRINGER. - 0138-9130 .- 1588-2861. ; 120:1, s. 283-300
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we compare two sophisticated publication-level approaches to ex-post citation normalization: an item-oriented approach and an approach falling under the general algorithmically constructed classification system approach. Using articles published in core journals in Web of Science (SCIE, SSCI & A&HCI) during 2009 (n=955,639), we first examine, using the measure Proportion explained variation (PEV), to what extent the publication-level approaches can explain and correct for variation in the citation distribution that stems from subject matter heterogeneity. We then, for the subset of articles from life science and biomedicine (n=456,045), gauge the fairness of the normalization approaches with respect to their ability to identify highly cited articles when subject area is factored out. This is done by utilizing information from publication-level MeSH classifications to create high quality subject matter baselines and by using the measure Deviations from expectations (DE). The results show that the item-oriented approach had the best performance regarding PEV. For DE, only the most fine-grained clustering solution could compete with the item-oriented approach. However, the item-oriented approach performed better when cited references were heavily weighted in the similarity calculations.
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