Ahlgren, Jarneving, and. Rousseau review accepted procedures for author co-citation analysis first pointing out that since in the raw data matrix the row and column values are identical i,e, the co-citation count of two authors, there is no clear choice for diagonal values. They suggest the number of times an author has been co-cited with himself excluding self citation rather than the common treatment as zeros or as missing values. When the matrix is converted to a similarity matrix the normal procedure is to create a matrix of Pearson's r coefficients between data vectors. Ranking by r and by co-citation frequency and by intuition can easily yield three different orders. It would seem necessary that the adding of zeros to the matrix will not affect the value or the relative order of similarity measures but it is shown that this is not the case with Pearson's r. Using 913 bibliographic descriptions form the Web of Science of articles form JASIS and Scientometrics, authors names were extracted, edited and 12 information retrieval authors and 12 bibliometric authors each from the top 100 most cited were selected. Co-citation and r value (diagonal elements treated as missing) matrices were constructed, and then reconstructed in expanded form. Adding zeros can both change the r value and the ordering of the authors based upon that value. A chi-squared distance measure would not violate these requirements, nor would the cosine coefficient. It is also argued that co-citation data is ordinal data since there is no assurance of an absolute zero number of co-citations, and thus Pearson is not appropriate. The number of ties in co-citation data make the use of the Spearman rank order coefficient problematic.

A quantitative survey of the literature pertaining to the study of public libraries, covering the period of 1986-2005, was pursued applying bibliometric methods. The survey aimed at the arrival of descriptive data that would inform about the features and development of the field’s base literature. It was found that the monographic form of cited references was more common than cited references of the journal form, but over time, the tendency to cite articles published in journals increased on behalf of monographs. In addition, the intellectual import from other fields than Library and Information Science was approximated and found more than marginal. On different levels of citation aggregations, frequency distributions and rank orders indicated a fragmented base literature. Cores of the more cited authors and journals were identified and illustrated by bibliometric mapping techniques. The exploration of a presumed shared intellectual focus on the earlier literature showed that approximately half of all papers were isolated in terms of not sharing references with any other paper, though a weak tendency of increased consensus was noted. Finally, though somewhat more than half of all citations were more than five years old, a tendency over time to cite more current literature was notable.

The method of author cocitation analysis (ACA) was first presented by White and Griffith in 1981 as a “literature measure of intellectual structure” and its applicability for the mapping of areas of science has since then been tested in various bibliometric science mapping studies. In this study, an experimental method of calculating the first or single author cocitation frequency is presented and compared with the standard method. Applying Ward’s method of clustering, the analysis revealed that the two approaches did not produce similar results and a tentative interpretation of deviations was that the experimental method provided with a more detailed depiction of the specialty structure. It was also concluded that a number of additional research questions need to be resolved before a comprehensive understanding of the suggested method’s merits and demerits is reached.

Based on previous findings and theoretical considerations, it was suggested that bibliographic coupling could be combined with a cluster method to provide a method for science mapping, complementary to the prevailing co-citation cluster analytical method. The complete link cluster method was on theoretical grounds assumed to provide a suitable cluster method for this purpose. The objective of the study was to evaluate the proposed method's capability to identify coherent research themes. Applying a large multidisciplinary test bed comprising more than 600,000 articles and 17 million references, the proposed method was tested in accordance with two lines of mapping. In the first line of mapping, all significant (strong) links connecting ‘core documents’ (strongly and frequently coupled documents) in clusters with any other core document was mapped. This resulted in a depiction of all significant artificially broken links between core documents in a cluster and core documents extrinsic to that cluster. The second line of mapping involved the application of links between clusters only. They were used to successively merge clusters on two subsequent levels of fusion, where the first generation of clusters were considered objects for a second clustering, and the second generation of clusters gave rise to a final cluster fusion. Changes of cluster composition on the three levels were evaluated with regard to several variables. Findings showed that the proposed method could provide with valid depictions of current research, though some severe restrictions would adhere to its application.

The method of bibliographic coupling in combination with the complete link cluster method was applied for mapping of the field of organic chemistry with the purpose of testing the applicability of a proposed mapping method on the field level. The method put forward aimed at the generation of cognitive cores of documents, so-called ‘bibliographic cliques’ in the network of bibliographically coupled research articles. The defining feature of these cliques is that they can be considered complete graphs where each bibliographic coupling link ties an unordered pair of documents. In this way, it was presumed that coherent groups of documents in the research front would be found and that these groups would be intellectually coherent as well. Statistical analysis and subject specialist evaluations confirmed these presumptions. The study also elaborates on the choice of observation period and the application of thresholds in relation to the size of document populations.

A citation analysis was applied to articles published in the Journal of the American Society for Information Science. The bibliographic data encompassed 427 genuine articles from the period 1973-1999. In order to find an intellectual foundation of information retrieval,a co-citation analysis of the most cited works of IR was carried out. In addition, current research themes of information retrieval clusters based on bibliographic coupling were analyzed.The results showed that the field of information retrieval mainly can be divided in two parts; one algorithmic and one user oriented. Essential concepts and research themes and their intertextual relations were identified. The author argues that citation analysis of bibliographical data can be used successfully as a guiding tool when studying a new curriculum or starting a research enterprice.

Motivated by the merging of four Swedish counties to a larger administrative and political unit with increased responsibilities, a comprehensive study of regional–foreign research collaboration was carried out. Various multivariate methods were applied for the depiction of collaborative networks of various compositions and at various levels of aggregation. Other aspects investigated concerned the influence of institutions and countries on regional–foreign collaboration and the relation between collaboration and research fields. Findings showed that foreign research collaboration was concentrated to three major regional institutions, each with a characteristic collaborative context. The influence of domestic collaboration was notable with regard to medical research while collaboration within the field of physics and astronomy was characteristic for pure regional–foreign collaboration, which was the dominating type of research collaboration throughout the period of observation (1998–2006).

The point of departure of Larsen's criticism is that the application of the whole counting method constitutes a 'problem of non-additivity'. This problem applies to the attribution of papers to unique institutions in address fields in bibliographic records representing Swedish research published during the period 1998-2006. The objective of this research was to visualize the regional publications structure and to provide a regional research profile based on national baselines. The points of criticism in Larsen's paper are reviewed in the same order as they appear in his critique.

This paper presents a citation analysis of the cognitive structure of current cardiovascularresearch. Used methods are co-citation analysis, bibliographic coupling and quantitative analysisof title words. Tables and graphs reveal: (1) The journal co-citation structure; (2) the cognitivecontent and the bibliometric structure of clusters based on co-citation; (3) the cognitive contentand the bibliometric structure of clusters based on bibliographic coupling. A predominance ofdifferent research aspects on coronary artery disease was found in clusters based on co-citations aswell as in clusters based on bibliographic coupling.

This thesis connects to previous research in bibliometric science mapping and citation indexing. A method was suggested for science mapping purposes and evaluated. The suggestion of this method was motivated by the fact that the prevailing method of citation based science mapping of documents, the cocitation cluster analytical method, can not map the most current published research, a feature that is a characteristic of the proposed method. On theoretical grounds, it was assumed that neither of these methods could substitute for the other and that they would have complementary functions in relation to one another. The prime objective was to evaluate the proposed method s capability to generate subject coherent clusters, i.e. to identify coherent research themes, and the assumed context of application was scientific information provision. The proposed method has two primary components: (1) a measure of document similarity, bibliographic coupling and (2) a cluster analytical method for the partition of document populations, the complete link cluster method. The research design comprised four different research settings of which three correspond to specific fields of research and one to a large multidisciplinary environment. Methods of evaluation comprised quantitative approaches as well as more qualitative ones. For the establishment of cluster coherence, measures of density and average coupling strength in clusters were applied. The relevance of generated clusters was assumed to be reflected by these measures and was substantiated by field experts evaluations of clustering results. In order to assess the agreement between field experts apprehensions of their fields cognitive structures, intellectual-manual partitions of document populations were performed by field experts and compared with partitions generated by the proposed method. Findings showed that the proposed method has the capability to identify and map current and coherent research themes on the level of a single research field as well as in a multidisciplinary environment. However, based on theoretical considerations as well as on empirical findings, it was concluded that it would not suffice as a standard science mapping method where exhaustive depictions of specialties cognitive structures are aimed at. The reasons for this were: i. As for now, the method of bibliographic coupling can not identify the most central concepts of a research specialty. ii. The dependency of consensual referencing implies that only minor shares of original document populations will be available for analysis. iii. The lack of a method for the decision of appropriate thresholds of coupling strength implies arbitrary threshold settings. iv. The partition of document populations brought about a fragmentation of research fields. v. Partitions generated by field experts deviated considerably from partitions generated by the complete link cluster method. It was therefore concluded that the proposed method may be complementary to the cocitation cluster analytical method and to traditional citation indexing. Based on the empirical findings, a tentative outline for such an application was given.

In this study a novel method of science mapping is presented which combines bibliographic coupling, as a measure of document-document similarity, with an agglomerative hierarchical cluster method. The focus in this study is on the mapping of so called ‘core documents’, a concept presented first in 1995 by Glänzel and Czerwon. The term ‘core document’ denote documents that have a central position in the research front in terms of many and strong bibliographic coupling links. The identification and mapping of core documents usually requires a large multidisciplinary research setting and in this study the 2003 volume of the Science Citation Index was applied. From this database, a sub-set of core documents reporting on the outbreak of SARS in 2002 was chosen for the demonstration of the application of this mapping method. It was demonstrated that the method, in this case, successfully identified interpretable research themes and that iterative clustering on two subsequent levels of cluster agglomeration may provide with useful and current information.

Introduction. A descriptive bibliometric study on a sub-national level with the aim to map a Swedish region's visibility and research collaboration during the observation period 1998-2006 was conducted. Method. Indicators and measures of research performance were constructed on basis of national standards. Results. Results show that the citation and publication patterns basically mirrored the national science and technology system, though some deviations were observed. The more influential science and technology fields were identified along with their more active regional producers of published research. A publication profile of the region was generated as well as a mapping of the balance between productivity and citation impact. Applying a research typology, different types of joint publishing and their relations to research areas were explored. Conclusions. The results are primarily of interest for local research policy but also of interest for a wider audience as a suggested method approach for similar regional assessment tasks.