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  • 1.
    Ahlgren, Per
    University College of Borås.
    A note on search formulation redundancy1998In: Journal of Documentation, ISSN 0022-0418, E-ISSN 1758-7379, Vol. 54, no 3, p. 352-354Article in journal (Refereed)
  • 2.
    Ahlgren, Per
    Stockholm University, Sweden.
    Den norska modellen sett från Sverige2008In: Forskningspolitikk, ISSN 0333-0273, Vol. 31, no 1, p. 18-18Article in journal (Other academic)
  • 3.
    Ahlgren, Per
    University College of Borås.
    On a cognitive search strategy1999In: Digital libraries: interdisciplinary concepts, challenges and opportunities, 1999, Vol. 1, p. 245-253Conference paper (Refereed)
  • 4.
    Ahlgren, Per
    University College of Borås.
    Passage retrieval: en introduktion till ett aktuellt forskningsområde2000In: Svensk biblioteksforskning, ISSN 0284-4354, E-ISSN 1653-5235, no 2, p. 5-20Article in journal (Other academic)
  • 5.
    Ahlgren, Per
    University College of Borås.
    Query expansion2001In: Human IT, ISSN 1402-1501, E-ISSN 1402-151X, no 4, p. 157-176Article in journal (Other academic)
  • 6.
    Ahlgren, Per
    University College of Borås.
    The effects of indexing strategy-query term combination on retrieval effectiveness in a Swedish full text database2004Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis deals with Swedish full text retrieval and the problem of morphological variation of query terms in thedocument database. The study is an information retrieval experiment with a test collection. While no Swedish testcollection was available, such a collection was constructed. It consists of a document database containing 161,336news articles, and 52 topics with four-graded (0, 1, 2, 3) relevance assessments.

    The effects of indexing strategy-query term combination on retrieval effectiveness were studied. Three of five testedmethods involved indexing strategies that used conflation, in the form of normalization. Further, two of these threecombinations used indexing strategies that employed compound splitting. Normalization and compound splittingwere performed by SWETWOL, a morphological analyzer for the Swedish language. A fourth combinationattempted to group related terms by right hand truncation of query terms. A search expert performed the truncation.The four combinations were compared to each other and to a baseline combination, where no attempt was made tocounteract the problem of morphological variation of query terms in the document database.

    Two situations were examined in the evaluation: the binary relevance situation and the multiple degree relevancesituation. With regard to the binary relevance situation, where the three (positive) relevance degrees (1, 2, 3) weremerged into one, and where precision was used as evaluation measure, the four alternative combinationsoutperformed the baseline. The best performing combination was the combination that used truncation. Thiscombination performed better than or equal to a median precision value for 41 of the 52 topics. One reason for therelatively good performance of the truncation combination was the capacity of its queries to retrieve different partsof speech.

    In the multiple degree relevance situation, where the three (positive) relevance degrees were retained, retrievaleffectiveness was taken to be the accumulated gain the user receives by examining the retrieval result up to givenpositions. The evaluation measure used was nDCG (normalized cumulated gain with discount). This measurecredits retrieval methods that (1) rank highly relevant documents higher than less relevant ones, and (2) rankrelevant (of any degree) documents high. With respect to (2), nDCG involves a discount component: a discount withregard to the relevance score of a relevant (of any degree) document is performed, and this discount is greater andgreater, the higher position the document has in the ranked list of retrieved documents.

    In the multiple degree relevance situation, the five combinations were evaluated under four different user scenarios,where each scenario simulated a certain user type. Again, the four alternative combinations outperformed thebaseline, for each user scenario. The truncation combination had the best performance under each user scenario.This outcome agreed with the performance result in the binary relevance situation. However, there were alsodifferences between the two relevance situations. For 25 percent of the topics and with regard to one of the four userscenarios, the set of best performing combinations in the binary relevance situation was disjunct from the set of bestperforming combinations in the multiple degree relevance situation. The user scenario in question was such thatalmost all importance was placed on highly relevant documents, and the discount was sharp.

    The main conclusion of the thesis is that normalization and right hand truncation (performed by a search expert)enhanced retrieval effectiveness in comparison to the baseline, irrespective of which of the two relevance situationswe consider. Further, the three indexing strategy-query term combinations based on normalization were almost asgood as the combination that involves truncation. This holds for both relevance situations.

  • 7.
    Ahlgren, Per
    Stockholm University.
    The SNIP indicator in relation to the Norwegian model2014In: Proceedings of the 19th International Conference on Science and Technology Indicators, 2014, p. 6-13Conference paper (Refereed)
  • 8.
    Ahlgren, Per
    Stockholm University.
    Two elements of evaluative bibliometrics in Sweden: The national indicator and the bibliometric unit of Stockholm University2015In: Ronald Rousseau and the development of Scientomerics in China.: The 8th International Conference on Scientometrics and  University Evaluation, 2015, p. 66-75Conference paper (Other academic)
  • 9.
    Ahlgren, Per
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE).
    Colliander, C.
    Sjögårde, Peter
    KTH, School of Education and Communication in Engineering Science (ECE). Department of ALM, Uppsala University, Uppsala, Sweden.
    Exploring the relation between referencing practices and citation impact: A large-scale study based on Web of Science data2018In: Journal of the Association for Information Science and Technology, ISSN 2330-1635, E-ISSN 2330-1643, Vol. 69, no 5, p. 728-743Article in journal (Refereed)
    Abstract [en]

    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.

  • 10.
    Ahlgren, Per
    et al.
    Stockholm University.
    Colliander, Cristian
    Document-document similarity approaches and science mapping: Experimental comparison of five approaches2009In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 3, no 1, p. 49-63Article in journal (Refereed)
  • 11.
    Ahlgren, Per
    et al.
    Stockholm University.
    Colliander, Cristian
    Textual content, cited references, similarity order, and clustering: An experimental study in the context of science mapping2009In: Proceedings of the 12th International Conference on Scientometrics and Informetrics (Volume 2), 2009, p. 862-873Conference paper (Refereed)
  • 12.
    Ahlgren, Per
    et al.
    Stockholm University, Sweden.
    Colliander, Cristian
    Persson, Olle
    Field normalized citation rates, field normalized journal impact and Norwegian weights for allocation of university research funds2012In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 92, no 3, p. 767-780Article in journal (Refereed)
    Abstract [en]

    We compared three different bibliometric evaluation approaches: two citation-based 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.

  • 13.
    Ahlgren, Per
    et al.
    Stockholm University.
    Grönqvist, Leif
    Evaluation of retrieval effectiveness with incomplete relevance data: theoretical and experimental comparison of three measures2008In: Information Processing & Management, ISSN 0306-4573, E-ISSN 1873-5371, Vol. 44, no 1, p. 212-225Article in journal (Refereed)
  • 14.
    Ahlgren, Per
    et al.
    University College of Borås.
    Grönqvist, Leif
    Measuring retrieval effectiveness with incomplete relevance data2006In: Current research in information sciences and technologies: multidisciplinary approaches to global information systems, 2006, p. 74-78Conference paper (Refereed)
  • 15.
    Ahlgren, Per
    et al.
    University College of Borås.
    Grönqvist, Leif
    Retrieval evaluation with incomplete relevance data: a comparative study of three measures2006In: Proceedings of the 15th ACM International Conference on Information and Knowledge Management, 2006, p. 872-873Conference paper (Refereed)
  • 16.
    Ahlgren, Per
    et al.
    Stockholm University.
    Hinders, Johan
    Lindelöw, Camilla
    Parmhed, Sara
    Swedberg, Per
    Research collaboration between Stockholm University and other Swedish academic institutions: a bibliometric study to support decisions on library collaboration2015In: Qualitative and Quantitative Methods in Libraries (QQML), ISSN 2241-1925, Vol. 4, p. 49-60Article in journal (Other academic)
    Abstract [en]

    Academic libraries collaborate in several ways. For instance, collaboration can concern standards for indexing and statistics, technical solutions or collection development. A question that a given academic library might ask is with which other academic libraries the library should principally collaborate. In this study, we show how bibliometric methods can be used to generate information that can support decision making with regard to the question at stake. We evaluate the amount of research collaboration between Stockholm University and other Swedish academic institutions across five publishing years, and for the whole considered time period, where research collaboration is operationalized as co-publishing. A dataset of publications obtained from Web of Science, where each publication has at least one Stockholm University address, is used in the study. Co-publishing rates, non-fractionalized and fractionalized, across the publishing years and for the whole for period, for Stockholm University and other Swedish academic institutions, are reported. Further, parts of the outcome of the study are visualized in terms of co-publishing networks.

  • 17.
    Ahlgren, Per
    et al.
    Stockholm University.
    Jarneving, Bo
    Bibliographic coupling, common abstract stems and clustering: a comparison of two document-document similarity approaches in the context of science mapping2008In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 76, no 2, p. 273-290Article in journal (Refereed)
  • 18.
    Ahlgren, Per
    et al.
    University College of Borås.
    Jarneving, Bo
    Rousseau, Ronald
    Author cocitation analysis and Pearson's r2004In: Journal of The American Society For Information Science And Technology, ISSN 1532-2882, E-ISSN 1532-2890, Vol. 55, no 9, p. 843-843Article in journal (Refereed)
  • 19.
    Ahlgren, Per
    et al.
    University College of Borås.
    Jarneving, Bo
    Rousseau, Ronald
    Rejoinder: In defense of formal methods2004In: Journal of The American Society For Information Science And Technology, ISSN 1532-2882, E-ISSN 1532-2890, Vol. 55, no 10, p. 936-936Article in journal (Refereed)
  • 20.
    Ahlgren, Per
    et al.
    University College of Borås.
    Jarneving, Bo
    Rousseau, Ronald
    Requirements for a cocitation similarity measure, with special reference to Pearson's correlation coefficient2003In: Journal of The American Society For Information Science And Technology, ISSN 1532-2882, E-ISSN 1532-2890, Vol. 54, no 6, p. 550-560Article in journal (Refereed)
    Abstract [en]

    Author cocitation analysis (ACA), a special type of cocitation analysis, was introduced by White and Griffith in 1981. This technique is used to analyze the intellectual structure of a given scientific field. In 1990, McCain published a technical overview that has been largely adopted as a standard. Here, McCain notes that Pearson's correlation coefficient (Pearson's r) is often used as a similarity measure in ACA and presents some advantages of its use. The present article criticizes the use of Pearson's r in ACA and sets forth two natural requirements that a similarity measure applied in ACA should satisfy. It is shown that Pearson's r does not satisfy these requirements. Real and hypothetical data are used in order to obtain counterexamples to both requirements. It is concluded that Pearson's r is probably not an optimal choice of a similarity measure in ACA. Still, further empirical research is needed to show if, and in that case to what extent, the use of similarity measures in ACA that fulfill these requirements would lead to objectively better results in full-scale studies. Further, problems related to incomplete cocitation matrices are discussed.

  • 21.
    Ahlgren, Per
    et al.
    Stockholm University, Sweden.
    Järvelin, Kalervo
    Measuring impact of twelve information scientists using the DCI index2010In: Journal of The American Society For Information Science And Technology, ISSN 1532-2882, E-ISSN 1532-2890, Vol. 61, no 7, p. 1424-1439Article in journal (Refereed)
    Abstract [en]

    The Discounted Cumulated Impact (DCI) index has recently been proposed for research evaluation. In the present work an earlier dataset by Cronin and Meho (2007) is reanalyzed, with the aim of exemplifying the salient features of the DCI index. We apply the index on, and compare our results to, the outcomes of the Cronin-Meho (2007) study. Both authors and their top publications are used as units of analysis, which suggests that, by adjusting the parameters of evaluation according to the needs of research evaluation, the DCI index delivers data on an author's (or publication's) "lifetime" impact or current impact at the time of evaluation on an author's (or publication's) capability of inviting citations from highly cited later publications as an indication of impact, and on the relative impact across a set of authors (or publications) over their "lifetime" or currently.

  • 22.
    Ahlgren, Per
    et al.
    University College of Borås.
    Kekälainen, Jaana
    Indexing strategies for Swedish full text retrieval under different user scenarios2007In: Information Processing & Management, ISSN 0306-4573, E-ISSN 1873-5371, Vol. 43, no 1, p. 81-102Article in journal (Refereed)
    Abstract [en]

    This paper deals with Swedish full text retrieval and the problem of morphological variation of query terms in the document database. The effects of combination of indexing strategies with query terms on retrieval effectiveness were studied. Three of five tested combinations involved indexing strategies that used conflation, in the form of normalization. Further, two of these three combinations used indexing strategies that employed compound splitting. Normalization and compound splitting were performed by SWETWOL, a morphological analyzer for the Swedish language. A fourth combination attempted to group related terms by right hand truncation of query terms. The four combinations were compared to each other and to a baseline combination, where no attempt was made to counteract the problem of morphological variation of query terms in the document database. The five combinations were evaluated under six different user scenarios, where each scenario simulated a certain user type. The four alternative combinations outperformed the baseline, for each user scenario. The truncation combination had the best performance under each user scenario. The main conclusion of the paper is that normalization and right hand truncation (performed by a search expert) enhanced retrieval effectiveness in comparison to the baseline. The performance of the three combinations of indexing strategies with query terms based on normalization was not far below the performance of the truncation combination. (c) 2006 Elsevier Ltd. All rights reserved.

  • 23.
    Ahlgren, Per
    et al.
    University College of Borås.
    Kekälainen, Jaana
    Swedish full text retrieval: Effectiveness of different combinations of indexing strategies with query terms2006In: Information retrieval (Boston), ISSN 1386-4564, E-ISSN 1573-7659, Vol. 9, no 6, p. 681-697Article in journal (Refereed)
    Abstract [en]

    In this paper, which treats Swedish full text retrieval, the problem of morphological variation of query terms in the document database is studied. The Swedish CLEF 2003 test collection was used, and the effects of combination of indexing strategies with query terms on retrieval effectiveness were studied. Four of the seven tested combinations involved indexing strategies that used normalization, a form of conflation. All of these four combinations employed compound splitting, both during indexing and at query phase. SWETWOL, a morphological analyzer for the Swedish language, was used for normalization and compound splitting. A fifth combination used stemming, while a sixth attempted to group related terms by right hand truncation of query terms. The truncation was performed by a search expert. These six combinations were compared to each other and to a baseline combination, where no attempt was made to counteract the problem of morphological variation of query terms in the document database. Both the truncation combination, the four combinations based on normalization and the stemming combination outperformed the baseline. Truncation had the best performance. The main conclusion of the paper is that truncation, normalization and stemming enhanced retrieval effectiveness in comparison to the baseline. Further, normalization and stemming were not far below truncation.

  • 24.
    Ahlgren, Per
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Publication Infrastructure.
    Pagin, Peter
    Persson, Olle
    Svedberg, Maria
    Bibliometric analysis of two subdomains in philosophy: free will and sorites2015In: SCIENTOMETRICS, ISSN 0138-9130, Vol. 103, no 1, p. 47-73Article in journal (Refereed)
    Abstract [en]

    In this study we tested the fruitfulness of advanced bibliometric methods for mapping subdomains in philosophy. The development of the number of publications on free will and sorites, the two subdomains treated in the study, over time was studied. We applied the cocitation approach to map the most cited publications, authors and journals, and we mapped frequently occurring terms, using a term co-occurrence approach. Both subdomains show a strong increase of publications in Web of Science. When we decomposed the publications by faculty, we could see an increase of free will publications also in social sciences, medicine and natural sciences. The multidisciplinary character of free will research was reflected in the cocitation analysis and in the term co-occurrence analysis: we found clusters/groups of cocited publications, authors and journals, and of co-occurring terms, representing philosophy as well as non-philosophical fields, such as neuroscience and physics. The corresponding analyses of sorites publications displayed a structure consisting of research themes rather than fields. All in all, both philosophers involved in this study acknowledge the validity of the various networks presented. Bibliometric mapping appears to provide an interesting tool for describing the cognitive orientation of a research field, not only in the natural and life sciences but also in philosophy, which this study shows.

  • 25.
    Ahlgren, Per
    et al.
    Stockholm University.
    Persson, Olle
    Globalization of citations and collaboration: A study of twelve journals2012In: Proceedings of the 17th International Conference on Science and Technology Indicators, 2012, Vol. 1, p. 23-32Conference paper (Refereed)
  • 26.
    Ahlgren, Per
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Publication Infrastructure.
    Persson, Olle
    Rousseau, Ronald
    An approach for efficient online identification of the top-k percent most cited documents in large sets of Web of Science documents2014In: ISSI Newsletter, ISSN 1998-5460, Vol. 10, no 4, p. 81-89Article in journal (Other academic)
  • 27.
    Ahlgren, Per
    et al.
    Stockholm University.
    Persson, Olle
    Tijssen, Robert
    Geographical distance in bibliometric relations within epistemic communities2013In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 95, no 2, p. 771-784Article in journal (Refereed)
  • 28.
    Ahlgren, Per
    et al.
    Stockholm University.
    Waltman, Ludo
    The correlation between citation-based and expert-based assessments of publication channels: SNIP and SJR vs. Norwegian quality assessments2014In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 8, no 4, p. 985-996Article in journal (Refereed)
    Abstract [en]

    We study the correlation between citation-based and expert-based assessments of journals and series, which we collectively refer to as sources. The source normalized impact per paper (SNIP), the Scimago Journal Rank 2 (SJR2) and the raw impact per paper (RIP) indicators are used to assess sources based on their citations, while the Norwegian model is used to obtain expert-based source assessments. We first analyze – within different subject area categories and across such categories – the degree to which RIP, SNIP and SJR2 values correlate with the quality levels in the Norwegian model. We find that sources at higher quality levels on average have substantially higher RIP, SNIP, and SJR2 values. Regarding subject area categories, SNIP seems to perform substantially better than SJR2 from the field normalization point of view. We then compare the ability of RIP, SNIP and SJR2 to predict whether a source is classified at the highest quality level in the Norwegian model or not. SNIP and SJR2 turn out to give more accurate predictions than RIP, which provides evidence that normalizing for differences in citation practices between scientific fields indeed improves the accuracy of citation indicators.

  • 29.
    Ahlgren, Per
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure.
    Yue, Ting
    Rousseau, Ronald
    Yang, Liying
    The role of the Chinese Key Labs in the international and national scientific arena revisited2017In: Research Evaluation, ISSN 0958-2029, E-ISSN 1471-5449, Vol. 26, no 2, p. 132-143Article in journal (Refereed)
    Abstract [en]

    In this contribution, which builds on and develops a study that was published more than 10 years ago, we address the role of the Chinese Key Labs (KLs) in the international and national scientific arena. We give a short overview of the position of KLs in China, including their budget and manpower. Based on large numbers of Chinese publications obtained from the Web of Science (WoS) and the Chinese Science Citation Database (CSCD), the KLs are compared across publication years to the rest of China (ChRest) with respect to publication output and citation impact. We also look at collaboration in terms of co-publishing between the KLs and the ChRest. As to publications in the WoS, we found that the contribution of KLs compared with the ChRest is slightly and irregularly increasing (using full counting as well as fractional counting), whereas a stronger increasing trend is observed for the corresponding contribution in the CSCD. We observed an increase in the number of collaborations between KLs and Chinese colleagues, regardless of database. For WoS and field normalized citation indicators, we obtained the expected results that researchers at KLs perform considerably better than other Chinese colleagues and, moreover, perform clearly better than database average. As such we may conclude that KLs have lived up to their promise and made real impact on the international arena.

  • 30.
    Colliander, Cristian
    et al.
    Umea Univ, Dept Sociol, Inforsk, Umea, Sweden.;Umea Univ, Univ Lib, Umea, Sweden..
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure. Uppsala Univ, Dept Stat, Uppsala, Sweden..
    Comparison of publication-level approaches to ex-post citation normalization2019In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 120, no 1, p. 283-300Article in journal (Refereed)
    Abstract [en]

    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.

  • 31. Colliander, Cristian
    et al.
    Ahlgren, Per
    Stockholm University.
    Experimental comparison of first and second-order similarities in a scientometric context2012In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 90, no 2, p. 675-685Article in journal (Refereed)
  • 32. Colliander, Cristian
    et al.
    Ahlgren, Per
    Stockholm University.
    The effects and their stability of field normalization baseline on relative performance with respect to citation impact: a case study of 20 natural science departments2011In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 5, no 1, p. 101-113Article in journal (Refereed)
  • 33.
    Ding, J.
    et al.
    National Science Library, Chinese Academy of Sciences.
    Shen, Z.
    National Science Library, Chinese Academy of Sciences.
    Ahlgren, Per
    Uppsala University, Department of Statistics.
    Tobias, Jeppsson
    KTH, Library.
    Minguillo, D.
    KTH, Library.
    How does author ethnic diversity affect scientific impact?: A study of nanoscience and nanotechnology2019In: 17th International Conference on Scientometrics and Informetrics, ISSI 2019 - Proceedings, International Society for Scientometrics and Informetrics , 2019, p. 2606-2607Conference paper (Refereed)
  • 34.
    Ding, Jielan
    et al.
    Chinese Acad Sci, Natl Sci Lib, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, 19A Yuquan Rd, Beijing 100049, Peoples R China..
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure. National Science Library, Chinese Academy of Sciences, Beijing, 100190, China.
    Yang, Liying
    Chinese Acad Sci, Natl Sci Lib, Beijing 100190, Peoples R China..
    Yue, Ting
    Chinese Acad Sci, Natl Sci Lib, Beijing 100190, Peoples R China.;Univ Chinese Acad Sci, 19A Yuquan Rd, Beijing 100049, Peoples R China..
    Disciplinary structures in Nature, Science and PNAS: journal and country levels2018In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 116, no 3, p. 1817-1852Article in journal (Refereed)
    Abstract [en]

    This paper analyzes, using Web of Science publications and two time periods (2004-2006 and 2014-2016), the disciplinary structures in the three prestigious journals Nature, Science and PNAS, compared with two baselines: Non-NSP_Multi (multidisciplinary publications that have other source journals than Nature, Science and PNAS), and Non-Multi (publications assigned to other categories than Multidisciplinary). We analyze the profiles at two levels, journal and country. The results for the journal level show that for Nature and Science, the publications are considerably less concentrated to certain disciplines compared to PNAS. Biology is the dominant discipline for all the three journals. Nature and Science have similar publication shares in Medicine, Geosciences, Physics, Space science, and Chemistry. The publications of PNAS are highly concentrated to two disciplines: Biology and Medicine. Compared with Non-NSP_Multi and Non-Multi, the shares of Biology in NSP journals are higher, whereas the share of Medicine is lower. At the country level, 14 countries are included, among them the five BRICS countries. With respect to the NSP journals, the emphasis disciplines (in terms of world share of publications) of most countries other than USA are the disciplines in which USA has its weakest performance. The disciplinary structures of USA and of most of the other studied countries therefore tend to be different. Regarding Non-NSP_Multi and Non-Multi, the shapes of the disciplinary structures of the 14 countries can be roughly grouped into three groups, while there are more types of shapes for the countries in the NSP journals. For all five units of analysis, the discipline structures of most countries generally change only slightly between different time periods. The structures of some BRICS countries, however, change to a relatively large extent.

  • 35. Sjögårde, P.
    et al.
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure.
    Granularity of algorithmically constructed publication-level classifications of research publications: Identification of topics2018In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 12, no 1, p. 133-152Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to find a theoretically grounded, practically applicable and useful granularity level of an algorithmically constructed publication-level classification of research publications (ACPLC). The level addressed is the level of research topics. The methodology we propose uses synthesis papers and their reference articles to construct a baseline classification. A dataset of about 31 million publications, and their mutual citations relations, is used to obtain several ACPLCs of different granularity. Each ACPLC is compared to the baseline classification and the best performing ACPLC is identified. The results of two case studies show that the topics of the cases are closely associated with different classes of the identified ACPLC, and that these classes tend to treat only one topic. Further, the class size variation is moderate, and only a small proportion of the publications belong to very small classes. For these reasons, we conclude that the proposed methodology is suitable to determine the topic granularity level of an ACPLC and that the ACPLC identified by this methodology is useful for bibliometric analyses. 

  • 36. Tong, S.
    et al.
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure.
    Evolution of three Nobel Prize themes and a Nobel snub theme in chemistry: a bibliometric study with focus on international collaboration2017In: Scientometrics, ISSN 0138-9130, E-ISSN 1588-2861, Vol. 112, no 1, p. 75-90Article in journal (Refereed)
    Abstract [en]

    In this study, three chemistry research themes closely associated with the Nobel Prize are bibliometrically analyzed—Ribozyme, Ozone and Fullerene—as well as a research theme in chemistry not associated with the Nobel Prize (a Nobel snub theme): Brunauer–Emmett–Teller equation. We analyze, based on an algorithmically constructed publication-level classification system, the evolution of the four themes with respect to publication volume and international collaboration, using two datasets, one of them a subset of highly cited publications, for each considered time period. The focus of the study is on international collaboration, where co-occurrence of country names in publications is used as a proxy for international collaboration. For all four themes, especially for Brunauer–Emmett–Teller equation, the publication volumes increase considerably from the earliest period to the later periods. The international collaboration rate shows an increasing trend for each theme. For Ozone, Fullerene and Brunauer–Emmett–Teller equation, the international collaboration rate tend to be higher for the highly cited publications compared to full datasets. With regard to the evolution of number of countries per international publication and per highly cited international publication, a vast majority of the distributions are positively skewed, with a large share of publications with two countries. With respect to the last four periods of the study, the concentration to two countries per publication is more pronounced for the Brunauer–Emmett–Teller equation theme compared to the three Nobel Prize themes. © 2017, The Author(s).

  • 37. Yang, Guo-liang
    et al.
    Ahlgren, Per
    Department for Library services, Language and ARC, KTH, School of Education and Communication in Engineering Science (ECE), Library, Publication Infrastructure.
    Yang, Li-ying
    Rousseau, Ronald
    Ding, Jie-lan
    Grading Countries/Territories Using DEA Frontiers2015In: PROCEEDINGS OF ISSI 2015 ISTANBUL: 15TH INTERNATIONAL SOCIETY OF SCIENTOMETRICS AND INFORMETRICS CONFERENCE, Leuven University Press, 2015, p. 436-447Conference paper (Refereed)
    Abstract [en]

    Several approaches exist related to categorizing academic journals/institutions/countries into different levels. Most existing grading methods use either a weighted sum of quantitative indicators (including the case of one properly defined quantitative indicator) or quantified peer review results. An important issue of concern for science and technology management is the efficiency of resource utilization. In this paper we deal with this issue and use multi-level frontiers of data envelopment analysis (DEA) models to grade countries/territories. Research funding and numbers of researchers as used as inputs, while papers and citations are output variables. The research results show that using DEA frontiers we can grade countries/territories on six levels. These levels reflect the corresponding countries' level of efficiency in S&T resource utilization. Furthermore, we use papers and citations as single outputs (with research funding and researchers as inputs) to show changes in country/territory level.

  • 38. Yang, Guoliang
    et al.
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure.
    Yang, Liying
    Rousseau, Ronald
    Ding, Jielan
    Reply to 'Comment on "Using multi-level frontiers in DEA models to grade countries/territories" by G.-I. Yang et al. [Journal of Informetrics 10(1) (2016), 238-253]'2017In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 11, no 3, p. 647-648Article in journal (Refereed)
  • 39. Yang, Guoliang
    et al.
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Publication Infrastructure.
    Yang, Liying
    Rousseau, Ronald
    Ding, Jielan
    Using multi-level frontiers in DEA models to grade countries/territories2016In: Journal of Informetrics, ISSN 1751-1577, E-ISSN 1875-5879, Vol. 10, no 1, p. 238-253Article in journal (Refereed)
    Abstract [en]

    Several investigations to and approaches for categorizing academic journals/institutions/countries into different grades have been published in the past. To the best of our knowledge, most existing grading methods use either a weighted sum of quantitative indicators (including the case of one properly defined quantitative indicator) or quantified peer review results. Performance measurement is an important issue of concern for science and technology (S&T) management. In this paper we address this issue, leading to multi-level frontiers resulting from data envelopment analysis (DEA) models to grade selected countries/territories. We use research funding and researchers as input indicators, and take papers, citations and patents as output indicators. Our research results show that using DEA frontiers we can unite countries/territories by different grades. These grades reflect the corresponding countries' levels of performance with respect to multiple inputs and outputs. Furthermore, we use papers, citations and patents as single output (with research funding and researchers as inputs), respectively, to show country/territory grade changes. In order to increase the insight in this approach, we also incorporate a simple value judgment (that the number of citations is more important than the number of papers) as prior information into the DEA models to study the resulting changes of these Countries/Territories' performance grades.

  • 40. Yue, T.
    et al.
    Yang, L.
    Ahlgren, Per
    KTH, School of Education and Communication in Engineering Science (ECE), Department for Library services, Language and ARC, Library, Publication Infrastructure.
    Ding, J.
    Shi, S.
    Frietsch, R.
    A comparison of citation disciplinary structure in science between the G7 countries and the BRICS countries2018In: Journal of Data and Information Science, ISSN 2096-157X, Vol. 3, no 3, p. 14-30Article in journal (Refereed)
    Abstract [en]

    This study aims to compare the characteristics of citation disciplinary structure between the G7 countries and the BRICS countries. In this contribution, which uses about 1 million Web of Science publications and two publications years (1993 and 2013), we compare the G7 countries and the BRICS countries with regard to this type of structure. For the publication year 2013, cosine similarity values regarding the citation disciplinary structures of these countries (and of nine other countries) were used as input to cluster analysis. We also obtained cosine similarity values for a given country and its citation disciplinary structures across the two publication years. Moreover, for the publication year 2013, the within-country Jeffreys-Matusita distance between publication and citation disciplinary structure was measured. First, the citation disciplinary structures of countries depend on multiple and complex factors. It is therefore difficult to completely explain the formation and change of the citation disciplinary structure of a country. This study suggests some possible causes, whereas detailed explanations might be given by future research. Second, the length of the citation window used in this study is three years. However, scientific disciplines differ in their citation practices. Comparison between citations across disciplines using the same citation window length may affect the citation discipline structure results for some countries. First, the results of this study are based on the WoS database. However, in this database some fields are covered to a greater extent than others, which may affect the results for the citation discipline structure for some studied countries. In future research, we might repeat this study using another database (like Scopus) and, in that case, we would like to make comparisons between the two outcomes. Second, the use of a constant journal set yielded that a large share of the journals covered by WoS year 2013 is ignored in the study. Thus, disciplinary structure is studied based on a quite restricted set of publications. The three mentioned limitations should be kept in mind when the results of this study are interpreted. Disciplinary structure on country level is a highlighted topic for the S&T policy makers, especially for those come from developing countries. This study observes the disciplinary structure in the view of academic impact, and the result will provide some evidence to make decision for the discipline strategy and funding allocation. Besides, Jeffreys-Matusita distance is introduced to measure the similarity of citation disciplinary structure and publication disciplinary structure. By applying this measure, some new observations were drawn, for example, "Based on the comparison of publication disciplinary structure and citation disciplinary structure, the paper finds most BRICS counties have less impact with more publications". The outcome of the cluster analysis indicates that the G7 countries and BRICS countries are quite heterogeneous regarding their citation disciplinary structure. For a majority of the G7 countries, the citation disciplinary structure tend to be more stable compared to BRICS countries with regard to the years 1993 and 2013. Most G7 countries, with United States as an exception, turned out to have lower values on the Jeffreys-Matusita distance than BRICS countries, indicating a higher degree of heterogeneity between the publication and the citation disciplinary structure for the latter countries. In other words, BRICS countries still receive much less citations in most disciplines than their publication output would suggest. G7 countries can still expect more citations than is to be expected based on their publication output, thereby generating relatively more impact than BRICS countries.

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