Trends in Research Librarianship Literature : A Social Network Analysis of Articles

Introduction The world is changing rapidly. Many factors, such as socio-economical, technological developments and globalization, designate the acceleration and direction of these changes. Academic disciplines need to revise their research areas and they must try to keep pace with the speed of these changes. Academic departments at universities could not stay out of these developments and research areas have been changing over time and also undergraduate programs are being revised. This can be named as scientific evolution and it usually engaged the attention of bibliometric researches. The bibliometrics aims to clarify the nature of scholarly communication and reveal the trends in scientific disciplines. Although new data sources such as Scopus and Google Scholar have been added to bibliometric environment in time, generally, citation indexes (Science Citation Index, Social Sciences Citation Index, Arts and Humanities Citation Index) serve as the primary data source for bibliometric researches.


Introduction
The world is changing rapidly.Many factors, such as socio-economical, technological developments and globalization, designate the acceleration and direction of these changes.Academic disciplines need to revise their research areas and they must try to keep pace with the speed of these changes.Academic departments at universities could not stay out of these developments and research areas have been changing over time and also undergraduate programs are being revised.This can be named as scientific evolution and it usually engaged the attention of bibliometric researches.The bibliometrics aims to clarify the nature of scholarly communication and reveal the trends in scientific disciplines.Although new data sources such as Scopus and Google Scholar have been added to bibliometric environment in time, generally, citation indexes (Science Citation Index, Social Sciences Citation Index, Arts and Humanities Citation Index) serve as the primary data source for bibliometric researches.
Bibliometricians aim to understand new trends in scholarly communication via articles and their references.The references or citations cumulatively show the most important topics that were dealt by the scholars.The process of scientific communication is affected by many factors, mainly information technologies, and the structure of scientific communication changes over time.In order to better understand the literature and the direction of new tendencies in different scientific disciplines, these changes and their impacts should be investigated.In this study the research librarianship literature was investigated by using bibliometric data, and findings were visualized by social network analysis method.

Literature Review
Many studies have examined research trends in different disciplines in the literature (Hu, Ma, Zhang, Gan, & Ho 2010;Ohniwa, Hibino, & Takeyasu 2010;Upham & Small 2010;Zhang, Xie, & Ho 2010).In these studies, along with various bibliometric analyses, co-word analyses of articles were conducted and the structures of disciplines were investigated.The recent researches begin to use social network analysis to represent data graphically.
Social network analysis is a method which is often used by disciplines of sociology, anthropology, communication, economics and mathematics.As an interdisciplinary research area, social network analysis is used to examine and describe the structure of communities.It also helps to visualize and model the relationships between communities which cannot be observed easily.The studies modeled by social network analysis focus on the contacts and relations within the communities (Freeman 2004;Scott 1988).
In a study which aimed to draw inferences on international collaboration by using co-author relationships (Leydesdorff & Wagner 2008), the articles published on 1990, 2000 and 2005 were investigated and the changes of the subjects of articles that were produced by collaborating authors from different countries were analyzed.The study showed that international collaboration in the production of scientific papers had increased significantly over time.It was also observed that the number of countries in the collaboration network was increasing as well.After the normalization, it was found out that France and Russia became prominent as important actors among other countries in terms of producing scientific publications (Leydesdorff & Wagner 2008, p. 321).In another study that analyzed the collaboration network of different countries in six different disciplines (astrophysics, geophysics, mathematical logic, polymers, soil science and virology), it was concluded that international connections might differ from discipline to discipline and the importance of forthcoming studies that would deal with co-authorship analysis in different disciplines was emphasized (Wagner 2005).
In addition to co-authorship analysis, there are also studies in the literature that work on author co-citations and map the intellectual structure of different scientific disciplines (McCain 1986;White & Griffith 1981).General assumption of this genre of studies is that the more the authors have co-citation, the stronger will be the bond they have.This means that the authors who have similar studies and receive co-citations over and over tend to cluster together on the map.Hereby, some inferences could be obtained such as, which author(s) groups' studies should be followed carefully.Similarly, by analyzing common terms in the documents, some maps related to the subjects which were studied in different fields could be produced (Van Den Besselaar & Heimeriks 2006).As these maps are examined in time, transitions and links among the disciplines as well as the thematic orientations are clearly emerging.
In social network analysis studies which use bibliometric data, variables such as articles, citations, co-citation networks, collaborating authors or institutions are examined and some concepts are widely used.One of them is "centrality" (Otte & Rousseau 2002, p. 441).There are different measures for centrality.Degree centrality, closeness centrality and betweenness centrality are among the most frequently used centrality measures.A unit's degree centrality indicates the number of links that the unit has.Closeness centrality, on the other hand, is the degree of the closeness of a unit to others directly or indirectly.Closeness is the sum of the inverse of a unit's shortest distance to other units.It also reflects how fast a unit can connect to other units in the network.Furthermore, betweenness is the degree of location of a unit among other units in a network.It shows in which level a unit is connected to other units that are not directly linked to each other.Any unit with a high degree of betweenness, act as an important bridge on the network (Otte & Rousseau 2002, pp. 442-443).In a study that used the Journal Citation Reports journals, it was concluded that the betweenness centrality for scientific journals is an indicator of the journals' multidisciplinary approach (Leydesdorff 2007(Leydesdorff , p. 1303)).For instance, important journals in a network of different scientific fields were identified by using degree centrality, closeness centrality and betweenness centrality techniques (Gao & Guan 2009).

Methodology
The purpose of this study is to identify the bibliometric characteristics of research librarianship literature and to visualize relationships in research librarianship.The data used in this study is obtained from Thomson Reuters' Social Sciences Citation Index (SSCI).We searched SSCI on January 20, 2010 to identify the "research librarianship" articles published in "Information Science & Library Science" category.To obtain the data, "research libra*" was entered in the "topic" field.Our study covers the years between 1956 (which is the publication year of first research librarianship related article in SSCI) and 2010.As a result, a total of 664 articles were identified (Figure 1).

Figure 1. Screenshot of the results page
It was seen that some journals have changed their names over time.To be able to make accurate evaluations, changes in the names of journals were determined and all the data belonging to the ones that changed their names were classified under their new names.Some examples are given in Table 1.In this research, we investigated the articles which were written on the "research librarianship" topic, within the scope of citation indexes.This study will therefore address the following research questions:  Who are the most productive and most cited authors in the field of research librarianship?What are the relationships among these authors? Which journals publish more articles on research librarianship and which ones are highly cited in the literature and can be named as the core journals in this field?
 What are the most frequently used words in the abstracts of articles related to research librarianship and what is the frequency of common usage of these words in different articles? Which new words related to research librarianship are added to the literature in time?
It is important to answer these questions because it ensures that new researchers, who study on research librarianship, can be aware of core journals and researchers, and the changes of research topics tendency.In addition to that, the outputs obtained from answers of these questions may help researchers to get to know closely the discipline of research librarianship.
After determining the research librarianship literature, the social network analysis method has been used to better understand the relations between authors and journals.CiteSpace application software which is designed as a tool for social network analysis has been used.CiteSpace is a Java application which analyzes and visualizes co-citation networks (Chen 2004).CiteSpace supports structural and temporal analyses of a variety of networks derived from scientific publications (Chen 2010).Publications, journals and authors networks have been examined by many studies via CiteSpace (Larsen 2008;Liang, Liu, Yang, & Wang 2008;Tonta & Darvish 2010).

Findings
There were 664 research librarianship articles indexed in the SSCI between the years 1956-2010.Figure 2 shows the gradual rise of articles related to research librarianship literature in five-year periods.The number of articles did not increase much until 1990s.A total of 222 articles were identified during the first 35 years , constituting only one-third of the total number of articles in this study.Yet the number of articles has more than doubled (442) within the last 20 years (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010), making up the remaining 67% of all articles under review.Research librarianship articles appeared in 58 different journals.More than 60% of the articles were published in nine different journals, while the rest appeared in 49 journals.There were nine journals which published 21 or more articles on research librarianship.Some 60% (399 articles) of all articles appeared in those nine journals listed in Table 2.The journal co-citation network contains the most frequently cited 629 journals and 4559 cocitation links among them.Figure 3   The majority (66%) of the articles had single authorship.This shows that research librarianship literature has a tendency for single authorship.Articles with multiple authors constituted 34% of all articles.There were 167 articles with two authors, 45 with three authors, and 11 with four authors.Only three articles had five or more authors.The highest number of contributors to a single article was eight.
The total number of different authors contributing to 664 articles was 840.Six percent of all articles were produced by the nine most prolific authors (Table 4).The overwhelming majority (90%) of authors contributed to the research librarianship literature with only a single article.The author co-citation network contains the most frequently cited 273 authors and 704 cocitation links among them.Figure 4 shows the authors who have high betweenness centrality.Among them; Herman Fussler, Eugene Garfield, Richard DeGennaro, Ralph E. Ellsworth and J. Periam Danton came to the fore since they have the highest betweenness centrality.This means these five authors are core nodes that make connections to other nodes in research librarianship literature network.On the other hand, Fussler, Ellsworth and Danton were not included in Table 5, where the most frequently cited 20 authors were listed.In this study, the network structure of words' co-occurrences in research librarianship has been revealed.For this process noun phrases were extracted from titles and abstracts of articles.The noun phrase of "research library" has a pivotal node and it is the most recurrent noun phrase.It is understood that the authors generally preferred to use the term "research library" instead of "academic library" or "university library".
The most frequently used words in the titles, abstracts, descriptors and identifiers are "research library", "collection development" and "electronic resources", respectively.It is observed that the highest centrality ratios of noun phrases are "research library", "information science", "collection development", and "university library" (Figure 6).There is not important new words related to research librarianship are added to the literature in time.
Particular noun phrases have continued to stay in use.Karen Schmidt, Tina Chrzastowski, Colleen Cook, Peter Hernon, Susan Lazinger, Richard Dougherty, Peter Graham, Mary Jackson, and Lewis Guodo Liu were the most prolific authors of research librarianship literature.On the other hand, the most cited author was Association of Research Librarianship as a corporate body.The study has also revealed the importance of this association.Peter Hernon seemed to be the prominent author because of productivity and citedeness.
Unfortunately, new research areas added to research librarianship literature in time were not visible in CiteSpace due to lack of efficient data.Presumably, if the keywords were not given with general terms and some articles did not lack abstracts, CiteSpace would have provided more significant results.

Figure 2 .
Figure 2. Number of research librarianship articles in the SSCI database (N = 664) displays the journals which have high betweenness centrality.College & Research Libraries has the highest centrality ratio (0.27) and papers which appeared in it have been cited since 1956 by the authors of research librarianship articles.Other highest betweenness centrality ratios belong to Library Journal (0.26), Communication (0.24), Libri (0.21), Zentralblatt für Bibliothekswesen (0.15), Library Resources & Technical Services (0.13), and Library Quarterly (0.13).This means these seven journals are core nodes that make connections to other nodes in research librarianship journal co-citation network.While College & Research Libraries, Library Journal, Libri, Library Resources & Technical Services, and Library Quarterly connect the core librarianship journals, Communication links journals that were not directly related to librarianship journals and, Zentralblatt für Bibliothekswesen connects German journals.

Figure 5 .
Figure 5.The network of co-cited documents on research librarianship (1956-2010) based on 11 five-year time slices

Figure 6 .
Figure 6.The network of co-occurred noun phrases in research librarianship literature(1956- 2010)

Table 1 .
Some of the journals that changed their names in time

Table 2 .
Journals published 21 or more articles on research librarianship

Table 3
provides the number of unique articles that cite a particular journal.College & Research Libraries has been cited in 231 different articles.This journal is followed by Journal of Academic Librarianship, Library Journal, Library Trends, respectively.College & Research Libraries is the most highly cited and the most preferred journal to make publications in research librarianship literature.As can be seen from Table2 and 3, Portal-Libraries and the Academy, Zentralblatt für Bibliothekswesen and Interlending & Document Supply, were not in the list of most frequently cited journals although they were three of the most preferred journals to make publications in research librarianship literature.In general, it could be said that authors' preferences of journals for publishing and citing seemed to be similar.

Table 3 .
Top 20 most frequently cited journals in research librarianship literature

Table 4 .
The most prolific authors of research librarianship Although one of the most cited authors in our study was a corporate body (Association of Research Libraries), corporate bodies were not included in Table4.Except Peter Hernon and Richard Dougherty, who were the most cited authors by different articles, Table does not include any authors from Table5.In general, it could be said that those who wrote articles and whose articles were cited were different people in research librarianship literature.

Table 5 .
Top 20 most frequently cited authors in research librarianship literature