Bibliometrics of social entrepreneurship research: Cocitation and bibliographic coupling analyses

Abstract The purpose of this paper is to provide conceptual structure, explore current research directions, and suggest emerging trends in social entrepreneurship. The authors ultilize co-citation analysis as well as bibliographic coupling analysis to analyze 1122 social entrepreneurship publications thought VOS Viewer software. Co-citation analysis was used to explore the structure of the research topic, while bibliographic coupling analysis was used to identify potential research topics. Based on themes from co-citation analysis and bibliographic coupling analysis, the authors compared similarities and differences between themes to explore potential research groups in SE, for instance, hybrid organizations, social value creation, dimensions, and measurement of social goals. This is the first study using co-citation analysis and bibliographic coupling analysis to review publications related to social entrepreneurship. This research study contributes to the social entrepreneurship literature by enhancing the understanding of the structures in social entrepreneurship through citations, as well as can be employed to support scholars in other for recognizing future research directions.


Introduction
The concept of "social entrepreneurship" (SE) has rapidly emerged in the private, public, and nonprofit sectors over the past decades, and interest in SE continues to flourish (Saebi et al., 2019). SE is an innovative solution to resolve the complicated demands of society (Chell, Spence et al., 2016). In fact, for developing countries, they tend to consider entrepreneurship as a solution for economic enhancements; however, this economic development leads to a series of diverse social problems for which the government has insufficient resources to solve (Chell, Spence et al., 2016). SE has a strong intuitive appeal and is of great interest from the academic community. However, this is still a new area as well as its research on SE lags far behind the practice (Mahfuz Ashraf et al., 2019). The variously excellent reviews were operated to capture the SE; nevertheless, these reconsiderations have a tendency to concentrate on precise components in SE, involving SE concepts and definitions (Bacq & Janssen, 2011), social innovation (Phillips et al., 2016), types of organization in SE (Doherty et al., 2014), social impact and social change (Rawhouser et al., 2019), or statistics of research study on SE (Rey-Martí et al., 2016). These findings cultivate certain insights about SE in expected aspects. Nonetheless, SE is widely distributed and at altered levels; this investigation indicates different approaches to summarize, classify, and suggest future research directions of SE studies through bibliometric methods, including co-citation analysis as well as bibliographic coupling analysis.
Bibliometrics is a statistical methodology that analyzes the basic information of documents such as authors, keywords, and references to impart insight into the development of a research topic (Nicolaisen, 2010;Van Raan, 2005). Bibliometrics methodology includes diverse techniques, for example, citation analysis, bibliographic coupling analysis, co-word analysis, and co-citation evaluation (Leung et al., 2017;Nicolaisen, 2010). To visualize the science map and support insights into the growth of SE literature, scholars combine two techniques of bibliometric method such as co-citation analysis and bibliographic coupling analysis.
With the assistance of bibliometrics, this work strives to investigate a dissimilar technique to provide conceptual structure, explore existing research directions, and recommend emerging trends in SE. This work has been applied co-citation analysis and bibliographic coupling analysis to analyze SE publications from the Web of Science (WoS) database. Co-citation analysis was used to explore the structure of the research topic, whereas bibliographic coupling analysis was utilized to indicate potential research circumstances. Especially, this research paper intends to accomplish the below objectives: 1) discover co-citation themes and visual co-citation network; 2) explore the bibliographic coupling themes and the visual bibliographic coupling network; 3) compared similarities and dissimilarities between themes between co-citation analysis and bibliographic coupling analysis to explore potential research directions in SE.

The conceptualization of social entrepreneurship
There are various definitions of SE that definitely converge on the combination of entrepreneurship and social mission (Cherrier et al., 2018), which is similar to the identification of chances and business activities to pursue social missions (Zahra et al., 2009).. Social goals are the main motivation for SE, it must solve social situations while ensuring profit, which results in a dual task of SE as well as social enterprises (Saebi et al., 2019). Mair & Noboa (2006) identify that SE involves an innovative approach to addressing social issues. Shane and Khurana (2003)'s was defined the definition of SE as a "process that begins with the formation of social ideas, identifying opportunities and solutions for sustainable social development". Last but not least, other scholars figure out more progressive perspectives of SE as business activities that combines the "social" and "entrepreneurship" to solve social problems with innovative solutions towards sustainable social development (Millman et al., 2010;Peredo & McLean, 2006;Shaker A Zahra et al., 2008).

Bibliometric analysis
The "bibliometric" is distinguished as "the application of mathematical and statistical methods to books and the other means of communication" . Moreover, the bibliometric admits researchers to analyze literature of research topic to find out the conceptual structure and the evolution of research themes (Castillo-Vergara et al., 2018;Leung et al., 2017). Bibliometric method has different techniques such as citation analysis, bibliographic coupling analysis, co-word analysis, and co-citation analysis (Van Eck & Waltman, 2009).
Combining different techniques in bibliometrics cultivates deeper insight into the research topics (Chang et al., 2015). The two common methods used together are bibliographic coupling analysis and co-citation analysis (Boyack & Klavans, 2010;Chang et al., 2015;Ferreira, 2018) that can be used to elucidate the intellectual structure of disciplines (Chang et al., 2015) (see Figure 1). Cocitation analysis is a technique that allows quantification of relationships and connections between articles, and it determines how often two articles are cited by a third article (Small, 1973), which is mentioned in the research paper of Benckendorff and Zehrer (2013). They also indicated that the co-citation is a measure of the relationship between the two publications through citations. Hence, research themes could be explored to provide more knowledge into the structure of academic literature (Leung et al., 2017). Regarding bibliographic coupling analysis, two articles are bibliographically coupled if they both cite one or more documents in their bibliographies. Two articles may treat a same subject if they are bibliographically coupled. Bibliographic coupling is a measure of the relationship between the two articles through "coupling strength". The "coupling strength" of two given articles is higher the more citations to other articles they share (Martyn, 1964). Several studies admit that co-citation analysis is more relevant in expressing the structure of the research topic than the bibliographic coupling analysis (Bichteler & Eaton, 1980). However, bibliographic coupling analysis has proven to be an appropriate method for identifying potential research topics (Zhao & Strotmann, 2008).

Method
Based on the advantages of co-citation analysis and bibliographic coupling analysis, the author uses a combination of these two methods to analyze SE research and identify potential research themes in the future (Leydesdorff et al., 2013). The data were taken through the Web of Science database, and the search terms used were "social entrep*". In fact, publications in English are considered without using any filters that were published before April 2021. In this work, a preliminary search returned 1541 publications and the scholars carefully read titles and abstracts of these 1541 publications to ensure that they are related to SE as well as to eliminate duplicates. Nonetheless, this research also has 419 publications that were excluded from the analysis, while a total of 1122 publications were retained for data analysis. Lastly, co-citation analysis was used to indicate key research themes in the field of SE, whereas bibliographic coupling analysis was used to analyze SE studies during the period when SE studies began to receive much attention to date.

Year of publication
According to Figure 2, it depicts the growth in the number of SE-related publications that was published from 1988 to 2021. As a result, the annual publication average is 40.07, indicating that SE is receiving more and more attention from the academic community.

Co-citation analysis
To establish a co-citation network comprising the most influential publications in the research of McCain (1990), who proposed establishing a cut point. After narrowing down the initial sample of 1122 articles to those articles containing at least 20 citations, the final sample comprises 190 articles. Correspondingly, this study analyzes co-citation from 190 articles.
Furthermore, the smart local moving algorithm method is used to exploit the structure of SE research (Cicea & Marinescu, 2021;Van Eck & Waltman, 2009), and the co-citation of the SE research is visualized in Figure 3. The size of the bubble represents the number of standardized citations that the articles receive and the thickness of the lines denoting the strength of citation relations. The link as well as the distance between two documents identify the co-citation relationship. Each color represents each theme to which the publication is linked. Author name and year of publication are labeled on each bubble (Waltman & Waltman, 2017).
The five studies with the highest indices of co-citation are:  The results of co-citation analysis showed that SE publications formed five themes as Table 1. The writer carefully read each typical article in each of those themes to name the themes. The first theme was the various concepts of SE and related issues, focusing on the birth of SE, its development, and comparison with other related concepts such as commercial entrepreneurship, public sector, social enterprise . . . The second theme referred to various issues of governance in SE such as strategy, collaboration, resource mobilization, technology, financial management, market orientation . . . The third theme presented social entrepreneurs and potential social entrepreneurs, the process from identifying opportunities to the intention to become a social entrepreneur. In addition, in this group, the factors that form a successful social entrepreneur are described. The fourth theme referred social innovation and social value in SE, explaining how SE impacts society to create social innovation, social change, and social value. The last theme referred to the institutional context, discussing the environmental factors affecting SE.

Bibliographic coupling
After narrowing down the initial sample of 1122 articles to those articles containing at least 20 citations, the final sample comprises 60 articles. Correspondingly, this study analyses bibliographic coupling in 190 articles The smart local moving algorithm method is also used to predict the direction of future research in bibliographic coupling analysis (Van Eck & Waltman, 2009). The bibliographic coupling of the SE research is visualized in Figure 4. The results of bibliographic coupling analysis showed that SE publications formed seven themes (Table 2).

Discussion, conclusions, and avenues for future research
Based on themes from co-citation analysis and bibliographic coupling analysis, the authors compared similarities and dissimilarities between themes to navigate hypothetical research groups in SE (see Table 3).
In addition, the first theme comes from bibliographic-coupling analysis shows a link to the first two themes in the co-citation analysis. The results from bibliographic-coupling analysis show the trend of conducting a review of SE studies. Many reviews were conducted with diverse approaches to provide in-depth knowledge of SE (Choi & Majumdar, 2014;Rey-Martí et al., 2016), especially SE definitions and issues related to governance in social enterprises are also concerned in relation to sustainable development.
There is a certain similarity between the third and the fourth theme in the co-citation analysis and the second and the third theme in the bibliographic coupling analysis. Social entrepreneurial intention and social innovation remain research directions that receive a lot of attention from scholars. Hence, the results from bibliographic coupling analysis show the emergence of crowd funding studies in SE. The upcoming research findings should focus on the background factors such as human capital, social capital, family background, education, role models and experience in relation to social entrepreneurial intention. Moreover, future studies must investigate extremely the role of the relationship between SE and social innovation; the impact of SE and social innovation on other aspects related to social innovations such as social movement, corporate social responsibility, economic development, and social change.
Regarding institutions and the environment in SE, this research focuses on understanding that country context facilitates SE (Stephan et al., 2015). In addition, the role of culture and the role of the business environment in social entrepreneurial orientation were also interested in this theme. More studies should be focused on Asian and African countries, where SE level is still low. Crosscultural studies are also necessary in the development of SE in different cultures. Future research must survey on various industries, cultures, interactions between culture and personal-level variables, and individuals from different ethnic backgrounds.
Emerging topics include hybrid organizations, social value creations, dimensions, and social measurements. Various discussions should be organized, which is essential for hybrid organizations. Likely, comparative analyses between diverse modes of organization regarding business model, value creation, and social value creation. Creating social values and the pursuit of social goals are a prerequisite task of social enterprises. The number of social enterprises is increasing steadily, but the social impacts have not been measured significantly by unified approaches. Thus, the upcoming surveys must take advantage of methodologies that can measure the creation of social values or social goals.
Overall, this research aims to apply both co-citation analysis and bibliographic coupling analysis in order to support the conceptual structures, investigate existing research directions, and suggest the emerging tendencies in SE. Otherwise, this study also contributes to the SE literature by categorizing SE studies, identifying highlighted trends in SE by co-citation analysis and bibliographic coupling analysis. However, the current study is not free from limitations. The usage of cocitation analysis and bibliographic coupling analysis might be misleading because it relies entirely on citations. The definition of themes depends on the evaluation of authors; thus, it might be biased. Some emerging tendencies might be ignored due to the deficiency of comprehensively collected publications. Consequently, future studies must utilize a combination of bibliometric analysis and other qualitative or quantitative approaches to achieve valuable knowledge from SE research.

This research is funded by Thu Dau Mot University
Author details Luc Phan Tan

Disclosure statement
No potential conflict of interest was reported by the author(s).