Prominent Themes and Blind Spots in Diversity and Inclusion Literature: A Bibliometric Analysis

The sample consists of 2510 publications written by 5340 different authors. While two or more authors wrote most publications, 532 were written by a single author. The publications have been published by 1965 different organizations in 449 different journals. 7778 keywords were used to describe the publications within our sample, and the sample has been cited 462,645 times, with an average of 40 citations per publication. The publication with the highest number of citations (1675) is Jehn et al. (1999). In total, 100 countries have contributed to research on D&I, which means the topic has considerable attention worldwide.

Figure 1 shows the number of publications on diversity and inclusion per year using a log scale. The first publication is from 1957, and since then, the body of knowledge on D&I has been growing exponentially. In the 1960s, the Civil Rights Movement addressed racial inequality with affirmative action as a result: policies or programs that aimed to provide opportunities to historically disadvantaged groups, such as women and racial minorities, in areas such as education, employment, and business, and end the preferential treatment to historically advantaged groups (Agocs & Burr, 1996; Dobbin & Kalev, 2021; Thomas, 1990). It is important to note that the early research and literature on diversity and inclusion in the US was more focused on racial groups than on gender. However, starting in the 1970s, there was a growing focus on ensuring equal rights for women in the workplace (Dobson et al., 2017), which evolved in more attention to gender diversity issues in affirmative action and research. This could explain the starting point of studying D&I within business and management.

In the late 1980s, the Workforce 2000 report stated that in the year 2000 only 15% of the net new labor market entrants would be White men (Johnston, 1987). In the following years, women and other minorities could contribute to the labor force but had few opportunities to further their careers in (middle) management or leadership positions (Clayton & Zetterberg, 2018; Thomas, 1990). This new organizational issue could explain the increase in publications since then.

In the years that followed, more attention was given to equal rights for men and women, and many European countries introduced legislation to have more women on corporate boards or political functions (Clayton & Zetterberg, 2018; Dobson et al., 2017). The start of the global financial crisis lowered trust in the status quo, so research on the effects of board diversity increased (Baker et al., 2020). This shift toward more research on board diversity had the most significant impact on increased attention to gender and diversity issues. The focus on diversity likely expanded from ethnic minorities and gender, to age, disability, religious, and LGBTQ+ issues. However, identifying individuals and their smaller numbers resulted in limited attention and publications on these topics. The significant impact slight drop in 2022 is explained by the fact that only the first half of 2022 has been included in the data set.

We examine the geographical development of D&I literature by identifying the countries and journals with the highest number of publications. First, we explore the number of publications and citations per country. The results are presented in Table 2. The United States of America has the highest number of publications (956) and citations (60,519) as one of the largest developed countries and the first to introduce AAP (Thomas, 1990); this can be expected (see Table 1). The United Kingdom is in second place regarding publications (291) and citations (9269). Except for the United States and Canada, all other countries have introduced a form of gender quotas (Baker et al., 2020; Clayton & Zetterberg, 2018). These ten countries are responsible for 88 percent of the total publications and include mainly Western countries. These results show that D&I literature has mainly focused on research in developed countries, especially where gender quotas are introduced.

Second, we identify the ten highest-publishing journals, the results of which are also presented in Table 1. These ten journals account for almost twenty percent of all publications, showing a higher density in the high-publishing countries than in journals. The leading journals are the Journal of Business Ethics (90 publications), the International Journal of Human Resource Management (66 publications), and Equality, Diversity, and Inclusion (65 publications). The level of quality, based on the number of citations, differs. The Academy of Management Journal (9894 citations) and the Journal of Business Ethics (7203 citations) are the highest-cited journals. Both in terms of publications and citations, the Journal of Business Ethics is an essential journal for publications on D&I. The journal Equality, Diversity, and Inclusion has a low citation score (260 citations) compared to its number of publications, but this can be explained by the fact that this is a relatively new journal, which was first published in 2017. Interestingly, four out of ten journals focus on Human Resources, indicating that D&I literature is mainly related to this topic.

To unravel the thematic development of D&I literature, we conduct several analyses. First, we aim to identify the highly cited publications to identify the core knowledge within D&I literature. Then, we conduct a keyword analysis to see what topics have been mainly researched and identify the main themes within the field. Table 2 shows the ten articles with the highest number of citations and includes a distinction between the number of GC and LC, where a high number of LC implies that a publication is highly relevant within the research field of D&I. Publications with a percentage of less than five percent of LC compared to GC were excluded. Based on Table 3, the articles by Harrison and Klein (2007), Jehn et al. (1999) and Pelled et al. (1999) are the most influential in the D&I research field. When we analyze the titles of these highly cited articles, we find that the words ‘performance’ and ‘effects’ or ‘outcomes’ of diversity occur in 8 out of 10 publications; none of the publications included the word ‘inclusion’ in its title. These results imply that the core knowledge within D&I literature has been on diversity, not inclusion, and its relation with (financial) performance.

The keyword analysis identified the most used keywords (see Table 4). Performance has the highest occurrence (465), followed by diversity (426), management (352), impact (288), and firm performance (278). The high occurrence of (firm) performance implies that the relationship with D&I is a much-researched topic, which other literature studies on diversity underline (Patrício & Franco, 2022; Reis et al., 2007). The most researched aspect of diversity is gender and adding the keywords gender (216), women (246), and gender diversity (199), they occur 661 times, higher than the number one keyword performance. This implies that gender diversity is the most researched topic within the D&I research field. The keyword inclusion occurs relatively little (137); this could be explained by the fact that inclusion is a new phenomenon within D&I literature (Nishii, 2013; Shore et al., 2018). These results underline the results of the most cited publications: the main focus of D&I literature is on diversity and its relation with performance; this analysis adds that most studies focus on gender diversity.

As we identified that previous studies have mainly focused on diversity, we are also interested in what specific attributes are researched. In the keyword analysis, only gender diversity comes up as one of the most used keywords. Therefore, we conduct an extra keyword analysis to examine what diversity attributes occur in D&I literature. We identified all keywords in our sample mentioning a diversity dimension and bundled them based on the dimension they signified. We identified 28 different terms corresponding to 14 dimensions, including the terms surface- and deep-level diversity (see Table 3).

Next, we grouped the dimensions into observable and nonobservable types of diversity (Milliken & Martins, 1996). Observable individual differences are race/ethnic background, nationality, gender, and age, and have been studied at all levels of the organization. Nonobservable diversity includes differences in personality characteristics, values, skills and knowledge, functional background, occupational background, industry experience, and organizational membership, and have been mainly researched in top management and boards (Milliken & Martins, 1996). Surface-level diversity corresponds to observable types of diversity, while deep-level diversity corresponds to nonobservable diversity (e.g., Harrison et al., 1998).

The results show that 88 percent of the keywords refer to observable types of diversity, with gender diversity occurring the most (735 times), followed by culture (176 times), race (159 times), ethnicity (98 times), and age (50 times). In regard to nonobservable types of diversity, the term deep-level diversity has the highest occurrence (105 times). Other nonobservable types of diversity, such as religion or sexual orientation, have been researched but occur relatively little in the sample. These results show that most previous studies have solely focused on observable types of diversity and, more specifically, gender diversity. This aligns with our previous keyword analysis, where gender diversity is the only dimension in the top 10 keywords.

To identify prominent themes in our sample, we conducted a keyword co-occurrence analysis, including all keywords with a minimum occurrence of 50. Keyword co-occurrence analysis is a method used to analyze the frequency and patterns of words appearing together in a given text or dataset. Words that frequently appear together often share contextual relevance. This analysis helps identify clusters of keywords, and by analyzing the keywords within each cluster, we can derive meaningful insights about the underlying themes connecting these articles. Using this method, we identified three prominent clusters that remained intact even when including keywords with lower occurrences. Figure 2 shows the results of this analysis, with the three main clusters in red, blue, and green. Table 5 shows an overview of these three clusters with corresponding keywords. The first cluster, in red, shows words closely related to diversity management; the most powerful associated words are diversity, management, and work. Other related words are gender, diversity management, managing diversity, and human resource management. These keywords imply that these publications focus on managing diversity within an organization or workplace. The keyword inclusion is also part of this cluster, which implies that diversity management and inclusion are closely related to one another, which is underlined by previous research (Yadav & Lenka, 2020). The second cluster, in green, can be related to team diversity. The keywords with the highest appearance are performance, conflict, relation demography, and workgroup diversity. These keywords relate to one another as diversity in teams is measured based on demographic diversity and deep-level diversity and the effects thereof on performance, conflict, job satisfaction, and turnover. The last cluster (3), in blue, mainly focuses on board diversity and the effects thereof on firm performance and corporate social responsibility. Board diversity mainly focuses on gender diversity, also described as women or women directors. The focus is on corporate governance and the role of (female) directors.

Table 6 presents the ten most popular publications, based on the highest ‘180 days usage count,’ which is the number of times a publication has been accessed or saved during this period (Janavi, 2020). The most popular publications are authored by Cucari et al. (2018), Liu et al. (2022) and Tang et al. (2021). This list consists of more recent publications than the ten most cited publications. It includes six publications focused on board or top management (gender) diversity, two on team diversity, one on inclusion, and one on performance. Moreover, five out of ten publications focus on the relationship between board diversity and corporate social responsibility (CSR). These results imply that current D&I academics are mainly focused on the role of diversity in boards and still mainly focus on gender diversity, in line with our previous results.

To further understand current research trends, we employed bibliographic coupling, a method that measures the similarity between academic articles based on shared references. When multiple articles reference the same set of key works, it suggests a thematic connection, indicating that those articles are likely exploring similar research topics (Donthu et al., 2021). By employing bibliographic coupling, we gain insights into the current dynamics and themes within our sample. The results, presented in Fig. 3, reveal the presence of 16 distinct clusters. The largest cluster, denoted in red and situated in the center-left, consisting of 669 publications, focused on team diversity and inclusion. Another cluster in green on the right, comprising 275 publications, emphasized board (gender) diversity. The blue cluster, positioned at the top with 214 publications, centered on diversity management. Additionally, the yellow cluster in the bottom-left corner, consisting of 40 items, explored an inclusive climate. Among these clusters, the purple cluster, with 14 items, was situated below the blue and green clusters and primarily examined the effects of diversity on firm performance. It is worth mentioning that the remaining ten clusters, each containing two to five items, were excluded from further analysis.

Based on the bibliographic coupling analysis, our findings highlight the prevalent themes in diversity and inclusion research. These themes include team diversity and inclusion, board diversity, diversity management, inclusive climate, and the effects of diversity. Notably, these themes align with the three themes we initially identified during the thematic development, which remain central to current research. However, recent studies have expanded the focus from solely diversity to encompass both diversity and inclusion, reflecting a shift in attention within the field.

The previous analyses identified the historical, geographical, thematic development, and current foci of D&I literature. Based on these results, we can also identify the blind spots in the literature. The results of the geographic development showed that almost ninety percent of publications root from developed countries. This implies that the role of D&I in developing countries remains under-researched, creating a blind spot for academics.

The thematic development shows several blind spots. First, the results showed three main themes in the literature, board diversity, team diversity, and diversity management. Interestingly, inclusion is not one of these central themes and—although closely related to diversity management—it is a very different concept. Second, this implies that the relationship between diversity and inclusion is unclear, creating another blind spot. Third, most previous studies have focused on gender diversity, leaving other dimensions under-researched, such as deep-level diversity and its underlying dimensions. Fourth, the results showed that most previous studies have solely focused on the role of diversity and its effect on (financial) performance. The effects of diversity on employees, social performance, and other stakeholders remain unknown. Finally, the literature does not include the determinants and antecedents for diversity and inclusion, so it remains to be seen what affects the level of D&I in organizations.

The analyses show no significant changes in focus themes over time: when we compare contemporary themes to the foundational themes, we identify only minor changes toward more research on inclusion. The foundational theme, team diversity, now also focuses on inclusion, and another theme has developed, focusing on inclusive climate. However, other aspects of inclusion still need to be explored, such as organizational inclusion or the relationship between diversity and inclusion. Next, we found that most studies still focus on the role of gender diversity, leaving other diversity dimensions as a blind spot in D&I literature.