利用Web of Science的主題分類，計算引用期刊的學科頻率分布能夠提供被引用期刊進行相似性比較的特徵，相較於共被引方法，這種相似性比較的維度較小，可以減少許多計算量。本研究比較Web of Science的資訊科學與圖書館學主題分類下的40種高影響力期刊，並以多維尺度法(multidimensional scaling)和階層式群集分析(hierarchical cluster analysis)比較比較所提出的方法與共被引方法的相似性估算結果。分析期刊的出版時間範圍為1987到2011，以5年為一個時期進行分析。在各期刊中，以Scientometrics (SCI)以及Journal of the Association for Information Science and Technology (JASIST)的引用期刊分布的學科最多元，因為JASIST有較廣的涵蓋範圍以及其他領域都對測量研究(metrics research)感到興趣。產生的映射圖與群集結果顯示某些期刊並不接近其他期刊。相似性估算結果顯示引用學科分析與共被引分析相似，各個時期兩種方法所得到的結果在分為三個群集的情況下，大多可以發現包含一個LIS群集、一個MIS群集以及一個較分散而邊緣的群集，不過組成群集的成員也有些不同，因此Wang and Wolfram (2014)建議可以引用學科分析做為共被引分析的補充。
The frequency distribution of disciplines by citing articles provides a signature for a cited journal that
permits it to be compared with other journals using similarity comparison techniques.
As an initial exploration, citing discipline data for 40 high-impact-factor journals assigned to the “information science and library science” category of the Web of Science were compared across 5 time periods. Similarity relationships were determined using multidimensional scaling and hierarchical cluster analysis to compare the outcomes produced by the proposed citing discipline and established cocitation methods.
The maps and clustering outcomes reveal that a number of journals in allied areas of the information science and library science category may not be very closely related to each other or may not be appropriately situated in the category studied.
The citing discipline similarity data resulted in similar outcomes with the cocitation data but with some notable differences. Because the citing discipline method relies on a citing perspective different from cocitations, it may provide a complementary way to compare journal similarity that is less labor intensive than cocitation analysis.
The application of visualization techniques to groups of bibliographic entities (publications, journals, or authors) provides a method for assessing the closeness of relationships among entities of interest. ... On a fundamental level, these investigations allow us to understand better the structure of disciplines based on the production of scholarship and how this changes over time (e.g., White & McCain, 1998). On a more specific level, findings can help to assess the impact of entities of interest or to situate disciplines or specializations within a larger context.
Leydesdorff and Cozzens (1993) studied how to delineate and attribute journals to specialties based on journal−journal citations and their changes over time. They demonstrated how the data could be used to construct macrojournals, consisting of aggregations of journals around a central journal.
Pudovkin and Garfield (2002) developed a journal relatedness factor based on citing and cited journals. The method was proposed to help identify thematically related journals.
Similarly, Glänzel and Schubert (2003) proposed the categorization of journals using a three-step process involving predefined categories, journal classification, and article classification for articles in journals with ambiguous subject assignments based on references.
Rafols and Leydesdorff (2009) compared the outcomes of two algorithms for the decomposition of large matrices against Web of Science (WoS) subject categories and Glänzel and Schubert’s categorization. The four methods resulted in similar map outcomes on a large scale.
Leydesdorff and Schank (2008) visualized and animated the disciplinary ties of three seed journals over time to demonstrate relationships among journals and their interdisciplinarity.
Boyack and Klavans (2010) compared results from cocitation analysis, bibliographic coupling, direct citation, and a hybrid approach for accuracy of outcomes in representing research fronts for a large corpus of biomedical literature. They noted that bibliographic coupling performed the best in representing the research fronts.
White (2000) proposed the use of citers to identify characteristics of a given author’s research such as an author’s citation identity, which consists of all the authors a given author cites. White also introduced the idea of citation image-makers, consisting of the authors who refer to a cited author. The citation image-makers approach may also be applied to journals, where citing authors constitute the citation image-makers of the journal.
Yan, Ding, Milojević, and Sugimoto (2012) explored community structures in IR research by combining topic modeling and community detection with IR literature to reveal the changing landscape of IR research.
To reduce the dimensionality of the similarity comparison, disciplinary identifiers for citing articles/journals may be used to reduce the number of comparisons that have to be made.
For the purposes of this study, WoS research areas are used. In this paper the research areas are referred to as disciplinary assignments.
This research is guided by several questions.
1. Does the frequency distribution of disciplines of citing journals permit comparison of journal similarities in a meaningful way?
2. Are the results of such a comparison similar or complementary to the better-established approach of cocitation analysis?
3. Do the similarities among journals within the same disciplinary categorization change over time as reflected in the changes in the frequency distribution of citing journal disciplines?
4. Can these similarities (or distances) provide decision support for whether journals should be grouped together in citation index services such as Thomson Reuters’ Journal Citation Reports?
Forty high-impact journals included in the Thomson Reuters’ 2011 Journal Citation Reports grouped in the category ISLS were selected for the study. ... In addition to many of the journals rated highly in library and information science (LIS), as evidenced by a perception study of LIS deans and Association of Research Library directors conducted by Nisonger and Davis (2005), this category includes journals in allied areas such as management information systems (MIS), geographic information systems, and medical informatics.
Among the 20 highest-impact journals listed in the ISLS category, only 3 are included in the top 20 journals rated by LIS deans based on their familiarity with these journals. The majority of the remaining journals in the top 20 based on impact factor could be argued to be from allied areas given their additional classification in other WoS research areas and the lack of familiarity or resulting lower prestige as determined by LIS deans.
Citing article/journal data were collected from 1987 to 2011 and were divided into 5-year intervals.
For each journal, all articles, review articles, and conference proceeding articles were selected; all other publication types such as cited material were excluded. For each time period, the “create citation report” in the WoS was selected to identify all citing articles. The number associated with “citing articles” was then selected to retrieve the list of citing articles. The WoS “analyze results” feature was next selected for the list of citing articles. On the results analysis page, “research areas” were selected as the ranking field to provide the tabulated list of citing disciplines. The ranked list of citing disciplines was then copied into an MS Excel spreadsheet.
The list of research areas and their frequencies represent the journal’s citing discipline profile for each time period.
Salton’s cosine similarity measures were calculated for each pair of journals to produce a symmetric
matrix of journal similarity values ranging between 0 and 1 (Ahlgren, Jarneving, & Rousseau, 2003, 2004; Egghe & Leydesdorff, 2009; Leydesdorff, 2006, 2007) for each time period.
To provide a baseline comparison, a cocitation analysis was also conducted with the same journals.
Multidimensional scaling (MDS) PROXSCAL analysis and hierarchical cluster analysis in SPSS v.20 were applied to the symmetric similarity matrices.
The PROXSCAL algorithm was used instead of ALSCAL for the MDS procedure because it allows similarity or dissimilarity matrices to be used and has been shown to provide superior results for cocitation studies (Leydesdorff & Vaughan, 2006).
For hierarchical clustering, Ward’s method was used. Minkowski distance and squared Euclidean distance were each explored and produced the same outcomes at the three-cluster level. Clustering outcomes were superimposed onto the MDS maps.
Library Resources and Technical Services (LRTS) consistently attracted citations from the fewest discipline areas, indicating a narrower interdisciplinary focus. In fact, the number of citing article disciplines has declined over the past decade for this journal, possibly indicating even narrower interdisciplinary impact.
Scientometrics (SCI) and the Journal of the Association for Information Science and Technology (JASIST), on the other hand, at different time periods each attract the most disciplinarily diverse citations. These outcomes are not unexpected given the broad coverage of JASIST and the interest in metrics research by other disciplines.
The MDS map of the journals using the proposed citing discipline approach for the first period appears in Figure 1. Among the journals, 14 of the 22 are situated in close proximity. A secondary group with three journals is situated on the periphery.
In combination with the cluster-analysis groupings, one can see at the three-cluster level that the tightly clustered journals are core to LIS.
A more widely dispersed second cluster of five journals consists of LIS and allied area journals in MIS. ... It is interesting to note that Government Information Quarterly (GIQ), International Journal of Geographical Information Science (IJGIS), and Journal of the Medical Library Association (JMLA)—at the time, still the Bulletin of the Medical Library Association–are situated more closely to and are clustered with the journals associated with the MIS area.
A peripheral “Other” cluster contains three journals. ... Telecommunication Policy (TP), Journal of Scholarly Communication (JSP), and Social Science Information (SSI) are situated on the periphery of the map for the first and second time periods, indicating little similarity with the other journals in the citing discipline distributions.
The equivalent cocitation analysis map (Figure 2) at the three-cluster level, produces similar outcomes, but with several notable differences.
The International Journal of Information Management (IJIM) is situated more closely to LIS journals than to those in MIS.
Two of the MIS journals are situated in their own cluster along with GIQ and TP, equivalent to the “other” category. IJGIS appears at the periphery of the map in the MIS category.
The remaining journals are subdivided into two clusters that may be characterized broadly as information science and library science, respectively, with JSP and SSI being a part of these clusters.
There is a 63.6% overlap (14 of 22 journals) in the cluster assignments, indicating that there is a moderate level of agreement between the two approaches.
For the second time period, the three clusters for the citing discipline-based analysis consisted of a group of 12 journals representing the LIS area, an emerging cluster of journals focusing on the MIS area and several journals in allied areas, and an “other” group consisting of JSP, SSI, TP, and IJGIS.
The cocitation analysis outcomes for the second time period reveal a similar mapping arrangement and clustering of journals, with 15 journals corresponding to the LIS category, eight representing a group with an MIS focus, and an “other” category consisting of journals in allied areas.
The citing discipline MDS map and cluster analysis results for the three-cluster level are similar to the first two time periods, but with more distinctive LIS, MIS, and other clusters as the number of journals in each cluster has grown.
The cocitation analysis map and resulting clusters at the three-cluster level consist of primarily LIS journals, those in MIS, and the other category similar in composition to the citing discipline outcome. ... The cluster assignment match at the three-cluster level between the citing discipline and cocitation analysis methods is 88% (29 of 33 journals), indicating a high level of agreement.
The citing discipline MDS map for the fourth time period is similar to that for the previous time period.
Of note with the cocitation cluster analysis outcome for the fourth time period is a much larger other category that includes a number of journals categorized as LIS by the citing discipline method. GIQ and INFSOC are situated between the LIS and MIS groups, although they are placed in the other group.
The citing discipline and cocitation maps for the fifth time period appear in Figures 5 and 6, respectively. The outcomes for the citing discipline approach are quite similar to those for the third and fourth time periods, with well-defined LIS and MIS categories and a more scattered other category on the periphery.
The three clusters based on the cocitation analysis data again reflect the LIS, MIS, and other groupings. There are fewer members in the other category than for the fourth time period
Much in the same way that dimensionality reduction used in certain statistical methods and IR allows for simplified comparisons, the use of the WoS research areas by citing journals and their frequency instead of citing authors or citing journals provides a less computationally intensive way to assess journal similarity by reducing the dimensionality of the comparisons and the computational overhead.
To reduce the dimensionality of the similarity comparison, disciplinary identifiers for citing articles/journals may be used to reduce the number of comparisons that have to be made.
For the purposes of this study, WoS research areas are used. In this paper the research areas are referred to as disciplinary assignments.
This research is guided by several questions.
1. Does the frequency distribution of disciplines of citing journals permit comparison of journal similarities in a meaningful way?
2. Are the results of such a comparison similar or complementary to the better-established approach of cocitation analysis?
3. Do the similarities among journals within the same disciplinary categorization change over time as reflected in the changes in the frequency distribution of citing journal disciplines?
4. Can these similarities (or distances) provide decision support for whether journals should be grouped together in citation index services such as Thomson Reuters’ Journal Citation Reports?
Forty high-impact journals included in the Thomson Reuters’ 2011 Journal Citation Reports grouped in the category ISLS were selected for the study. ... In addition to many of the journals rated highly in library and information science (LIS), as evidenced by a perception study of LIS deans and Association of Research Library directors conducted by Nisonger and Davis (2005), this category includes journals in allied areas such as management information systems (MIS), geographic information systems, and medical informatics.
Among the 20 highest-impact journals listed in the ISLS category, only 3 are included in the top 20 journals rated by LIS deans based on their familiarity with these journals. The majority of the remaining journals in the top 20 based on impact factor could be argued to be from allied areas given their additional classification in other WoS research areas and the lack of familiarity or resulting lower prestige as determined by LIS deans.
Citing article/journal data were collected from 1987 to 2011 and were divided into 5-year intervals.
For each journal, all articles, review articles, and conference proceeding articles were selected; all other publication types such as cited material were excluded. For each time period, the “create citation report” in the WoS was selected to identify all citing articles. The number associated with “citing articles” was then selected to retrieve the list of citing articles. The WoS “analyze results” feature was next selected for the list of citing articles. On the results analysis page, “research areas” were selected as the ranking field to provide the tabulated list of citing disciplines. The ranked list of citing disciplines was then copied into an MS Excel spreadsheet.
The list of research areas and their frequencies represent the journal’s citing discipline profile for each time period.
Salton’s cosine similarity measures were calculated for each pair of journals to produce a symmetric
matrix of journal similarity values ranging between 0 and 1 (Ahlgren, Jarneving, & Rousseau, 2003, 2004; Egghe & Leydesdorff, 2009; Leydesdorff, 2006, 2007) for each time period.
To provide a baseline comparison, a cocitation analysis was also conducted with the same journals.
Multidimensional scaling (MDS) PROXSCAL analysis and hierarchical cluster analysis in SPSS v.20 were applied to the symmetric similarity matrices.
The PROXSCAL algorithm was used instead of ALSCAL for the MDS procedure because it allows similarity or dissimilarity matrices to be used and has been shown to provide superior results for cocitation studies (Leydesdorff & Vaughan, 2006).
For hierarchical clustering, Ward’s method was used. Minkowski distance and squared Euclidean distance were each explored and produced the same outcomes at the three-cluster level. Clustering outcomes were superimposed onto the MDS maps.
Library Resources and Technical Services (LRTS) consistently attracted citations from the fewest discipline areas, indicating a narrower interdisciplinary focus. In fact, the number of citing article disciplines has declined over the past decade for this journal, possibly indicating even narrower interdisciplinary impact.
Scientometrics (SCI) and the Journal of the Association for Information Science and Technology (JASIST), on the other hand, at different time periods each attract the most disciplinarily diverse citations. These outcomes are not unexpected given the broad coverage of JASIST and the interest in metrics research by other disciplines.
The MDS map of the journals using the proposed citing discipline approach for the first period appears in Figure 1. Among the journals, 14 of the 22 are situated in close proximity. A secondary group with three journals is situated on the periphery.
In combination with the cluster-analysis groupings, one can see at the three-cluster level that the tightly clustered journals are core to LIS.
A more widely dispersed second cluster of five journals consists of LIS and allied area journals in MIS. ... It is interesting to note that Government Information Quarterly (GIQ), International Journal of Geographical Information Science (IJGIS), and Journal of the Medical Library Association (JMLA)—at the time, still the Bulletin of the Medical Library Association–are situated more closely to and are clustered with the journals associated with the MIS area.
A peripheral “Other” cluster contains three journals. ... Telecommunication Policy (TP), Journal of Scholarly Communication (JSP), and Social Science Information (SSI) are situated on the periphery of the map for the first and second time periods, indicating little similarity with the other journals in the citing discipline distributions.
The equivalent cocitation analysis map (Figure 2) at the three-cluster level, produces similar outcomes, but with several notable differences.
The International Journal of Information Management (IJIM) is situated more closely to LIS journals than to those in MIS.
Two of the MIS journals are situated in their own cluster along with GIQ and TP, equivalent to the “other” category. IJGIS appears at the periphery of the map in the MIS category.
The remaining journals are subdivided into two clusters that may be characterized broadly as information science and library science, respectively, with JSP and SSI being a part of these clusters.
There is a 63.6% overlap (14 of 22 journals) in the cluster assignments, indicating that there is a moderate level of agreement between the two approaches.
For the second time period, the three clusters for the citing discipline-based analysis consisted of a group of 12 journals representing the LIS area, an emerging cluster of journals focusing on the MIS area and several journals in allied areas, and an “other” group consisting of JSP, SSI, TP, and IJGIS.
The cocitation analysis outcomes for the second time period reveal a similar mapping arrangement and clustering of journals, with 15 journals corresponding to the LIS category, eight representing a group with an MIS focus, and an “other” category consisting of journals in allied areas.
The citing discipline MDS map and cluster analysis results for the three-cluster level are similar to the first two time periods, but with more distinctive LIS, MIS, and other clusters as the number of journals in each cluster has grown.
The cocitation analysis map and resulting clusters at the three-cluster level consist of primarily LIS journals, those in MIS, and the other category similar in composition to the citing discipline outcome. ... The cluster assignment match at the three-cluster level between the citing discipline and cocitation analysis methods is 88% (29 of 33 journals), indicating a high level of agreement.
The citing discipline MDS map for the fourth time period is similar to that for the previous time period.
Of note with the cocitation cluster analysis outcome for the fourth time period is a much larger other category that includes a number of journals categorized as LIS by the citing discipline method. GIQ and INFSOC are situated between the LIS and MIS groups, although they are placed in the other group.
The citing discipline and cocitation maps for the fifth time period appear in Figures 5 and 6, respectively. The outcomes for the citing discipline approach are quite similar to those for the third and fourth time periods, with well-defined LIS and MIS categories and a more scattered other category on the periphery.
The three clusters based on the cocitation analysis data again reflect the LIS, MIS, and other groupings. There are fewer members in the other category than for the fourth time period
Much in the same way that dimensionality reduction used in certain statistical methods and IR allows for simplified comparisons, the use of the WoS research areas by citing journals and their frequency instead of citing authors or citing journals provides a less computationally intensive way to assess journal similarity by reducing the dimensionality of the comparisons and the computational overhead.
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