Relevance of documents, authors, sources, countries and organizations
The papers authored by Banke-Thomas et al. (2015) and Hall et al. (2015) are undoubtedly top references in the field of SROI studies. These two articles have the highest normalized number of citationsFootnote 3 compared to other studies listed in Table 1, which presents the most cited documents. This underscores their substantial impact and influence within the research domain.
Maria Merino, Rhiannon Tudor Edwards, and Álvaro Hidalgo-Vega emerge as the most prolific authors in the list of 288 papers, with 10, 9, and 8 documents published, respectively. Table 2, however, showcases the top 10 authors in the field of SROI based on their impact, measured by the number of citations they have received. This Table was created using a thesaurus fileFootnote 4. As anticipated, the top positions in this ranking are occupied by the authors of the most cited publication: Ross Millar (University of Birmingham, UK) and Kelly Hall (University of Northampton, UK). Notably, Matthew Hall (London School of Economics, UK), along with Aduragbemi Banke-Thomas, Barbara Madaj, and Nynke van den Broek (all from the University of Liverpool, UK), featured in Table 1 among the most cited publications, also reappear in the listing of Table 2 with impressive citation and normalized citation numbers. These authors have made significant contributions to SROI research, as evidenced by their substantial citation counts.
Table 3 contains the ten journals that have published at least 3 articles on SROI. Only one of the journals from Table 1, which listed the most cited publications, appears here, namely BMC Public Health. Sustainability is the most prolific journal, with 16 documents, although Voluntas leads in terms of received citations. When these citations are normalized, Sustainability then takes the lead again. The Table includes the Journal Impact Factor for 2022, and The Lancet, with 4 publications on SROI, stands out well above the others, with an Impact Factor of 168.9. If we look at the data from category rankings in JCR 2022, most of the journals are in the health field, followed by journals in social issues (Evaluation and Program Planning and Voluntas), and finally, there is only one journal in environmental studies (Sustainability) and one in public administration (Nonprofit Management & Leadership). The health journals top the Impact Factor and quartile rankings.
Table 4 presents an analysis of the 10 most prolific countries in terms of research publications on SROI. Some countries are not shown in this Table because they have published fewer documents. However, they have received a significant number of citations: the Netherlands, for instance, has 78 citations to its 6 documents. However, the correlation coefficient between the number of publications and the received citations is high (92.11%) for countries that have published more than 5 documents on SROI. Data of normalized citations confirm this ranking, with England and USA at the top in terms of documents, citations, and normalized citations. The variable link between two countries measures the times one country cites the other.
Table 5 offers detailed information about the authors’ affiliations, highlighting the institutions with which they are associated. The table is organized by the number of citations received and includes the top 10 positions in the analysis. Based on the figures for normalized citationsFootnote 5, the top three institutions in the ranking are the Università degli Studi di Firenze (Italy), Bangor University (Wales), and Boston University (USA). If we examine the variable citations, Bangor University is replaced on the podium by Arizona State University (USA). Analyzing normalized citations seems more appropriate, as normalization corrects for the fact that older documents have had more time to accumulate citations than recent ones. The institutions listed in Table 5 also demonstrate multiple citation links, where one institution cites the other, a pattern similar to the findings in Table 4.
Co-occurrence network analysis
Co-occurrence analyses are quite valuable for identifying the most relevant terms within SROI research. The visualization of the mapping provides a comprehensive overview of the relationships between terms and the formation of clusters. This view helps identify distinct clusters of related topics, enabling researchers to gain insights into the main research directions within the study of SROI.
The unit of our study is the term. When creating concept maps from a text corpus, users can choose between binary counting and full counting. With binary counting, the software indicates the number of documents in which a term occurs at least once. In the case of full counting, the software indicates the total number of occurrences of a term across all documents. Our decision to use binary counting aligns with the recommendation by Polley (2016).
The program selects 156 terms with at least 10 occurrences to be extracted from the title and the abstract. The sample is then manually refined using a thesaurus file, which helps eliminate general terms such as “author” or “example”, merge synonyms (e.g., SROI method and SROI methodology), and correct spelling variations (e.g., organization and organisation). Following this process, 141 unique terms are obtained, and the program selects 60% of the most relevant terms, resulting in 85 terms retained.
The software employs distance-based mapping techniques to create a network visualization of co-occurring terms, as illustrated in Fig. 5. The distance is proportional to the relatedness, and the size shows the number of repetitions (occurrences) of each term. Additionally, the lines represent the number of times the terms appear together (links). Moreover, the thickness of these lines represents the intensity of this relationship, with thicker lines indicating more frequent occurrences together. Four distinct clusters, each comprising at least fourteen terms, are identifiedFootnote 6.
SROI: network visualization of co-occurring terms.
The map displays multiple connections, reflecting the diverse treatment of the topic across different areas and perspectives. Map clusters can be linked to specific subtopics. The green cluster consolidates work related to accounting, including ratios, or monetary value. Here can be found the comparison of Nicholls (2017) with other approaches, primarily cost–benefit analysis. Notably, the term with the highest number of links in this cluster is SROI analysis, positioned closely to the blue cluster. This blue cluster emphasizes how SROI is connected to social issues such as women, persons, health, or family. The most frequently occurring terms (largest nodes) in this cluster are person, service, and health. The red cluster encompasses studies on methodological issues, elucidating its connections to theory, practice, measurement, or indicators. The smaller yellow cluster, comprising 14 terms, represents a specific line of research focused on efficiency and strategy issues.
Both Figs. 5 and 6 analyze the co-occurring terms extracted from SROI publications. However, while Fig. 5 displays the clusters of terms, Fig. 6 illustrates the evolution over time (2015–2022) using an overlay visualization of a map, where terms are colored according to a specific score; in this case, the years.
SROI: temporal overlay visualization of co-occurring terms in publications.
In Fig. 6, the early years are represented with cool colors, while the recent years are represented with warm colors. The dispersion on the map is evident, with a clear shift in recent years towards a monetary focus (dollar, euro, strategy) and health-based (health, wellbeing), in contrast to the earlier years, which were more centered around business (employment, organization, social enterprise), contribution, and knowledge.
To deepen the analysis, we selected enterprise as a representative term of the early years and health as a representative term of the more recent years. We conducted annual co-occurrence analyses and tabulated the number of co-occurrences for these terms. We then projected the future number of co-occurrences using a linear trend, as shown in Fig. 7. We also included the term mental health in the analysis, as it has emerged as a relevant topic in recent years (notably absent in the early years, as shown in the figure). As shown, the co-occurrences of the term enterprise follow a decreasing trend, while those related to health show an increasing trend.
SROI: Future trend of significant co-occurring terms.
Co-citation analysis
The co-citation analysis is an effective method for evaluating the foundations of SROI research by analyzing citation patterns within the literature. A fundamental assumption of co-citation analysis is that the more two items (references or sources) are cited together, the more likely it is that their content is related (Zupic and Čater, 2015). In the first analysis (Fig. 8), the analysis unit is the cited references of the papers in the sample, where the relatedness of the references in the map is determined by the number of times they are cited together in the same document. The closer two publications are located to each other, the more frequently these publications tend to be listed in the investigated bibliographies. The size of the node is proportional to the number of citations. To perform the counting, the software offers the possibility to choose between full counting and fractional counting. Fractional counting reduces the influence of documents with a large number of authors. Our choice has been to use fractional counting for the analysis, following the recommendation by Perianes-Rodriguez et al. (2016).
SROI: network visualization of co-citation (cited references).
Figure 8 on cited references displays three distinct clusters. The green cluster on the right focuses on SROI and health, with Banke-Thomas et al. (2015) standing out as a leader in citations and co-citations. The red cluster on the left consolidates guides for calculating SROI, with Nicholls et al. (2012) centrally positioned on the map and linked to publications from all clusters. Notably, Millar and Hall (2013), the most cited publication in Table 1, is found in this cluster. Lastly, the blue group at the top gathers documents that analyze measures and evaluations of SROI.
Figure 9 depicts the network by considering the cited sources of the documents as the unit of analysis. The relatedness of journals in the map is determined by the number of times they are cited together in the same document. The size of each node is proportional to the number of citations. For construction, a minimum of 10 citations for a cited source were chosen.
SROI: network visualization of co-citation (cited sources).
In Fig. 9, out of the 6018 sources, considering 20 as the minimum number of citations for a source, three clusters emerge: the red cluster on the left with 19 items, the green cluster on the right with 10 items, and the blue cluster at the top with 8 items. The green cluster emphasizes journals related to health (e.g., BMC Public Health with the highest number of citations in this cluster -120-, BMC Health Services Research, or The Lancet). The red cluster encompasses numerous journals oriented towards social, accounting, and non-profit issues (e.g., Social Enterprise Journal with the highest number of citations in this cluster -134-, Voluntas, Nonprofit Management and Leadership, Accounting, Organizations & Society, or the Journal of Business Ethics), while the blue cluster includes journals focused on sustainability issues such as Sustainability, with the highest number of citations in this cluster -118-, the Journal of Cleaner Production, or Ecological Economics.