Does increased diversity among doctoral cohorts improve research innovation?

Increased diversity among doctoral cohorts is associated with higher research innovation, but systemic barriers often limit the full realisation and recognition of these benefits.

1. Introduction

The relationship between diversity in doctoral cohorts and research innovation has been the subject of extensive empirical and theoretical investigation. Multiple large-scale studies demonstrate that increased demographic, disciplinary, and cognitive diversity among doctoral students and research teams is associated with higher rates of scientific novelty, more creative outputs, and greater research impact (Hofstra et al., 2019; Yang et al., 2022; AlShebli, Rahwan and Woon, 2018; Wang et al., 2019; Liu et al., 2025; Specht and Crowston, 2022). For example, analyses of over a million US PhD recipients reveal that underrepresented groups (by gender and race) produce more novel scientific contributions, though these innovations are often undervalued and less likely to lead to academic advancement (Hofstra et al., 2019; McCartney, 2020; Hofstra et al., 2019). Gender-diverse and ethnically diverse teams consistently outperform homogeneous groups in terms of research novelty and citation impact (Yang et al., 2022; AlShebli, Rahwan and Woon, 2018; Nielsen et al., 2017; Nielsen, Bloch and Schiebinger, 2018). However, the literature also highlights a “diversity–innovation paradox,” where the innovative contributions of diverse cohorts are discounted or less likely to be rewarded within academic systems (Hofstra et al., 2019; Hofstra et al., 2019; Gibbs et al., 2016). Interdisciplinary and international diversity further enhance innovation, especially when supported by inclusive environments and effective team integration (Smolock and Robert, 2020; Carr, Loucks and Blöschl, 2018; Specht and Crowston, 2022; Trechsel et al., 2021). Despite these benefits, challenges such as bias, lack of inclusion, and structural barriers persist, limiting the full potential of diversity-driven innovation (Puritty et al., 2017; Olzmann, 2020; Boghdady, 2025). Overall, the evidence strongly supports the positive impact of increased diversity in doctoral cohorts on research innovation, while also emphasising the need for systemic changes to fully realise these gains.

2. Methods

To explore the relationship between diversity in doctoral cohorts and research innovation, a systematic review of the existing scholarly literature was conducted. Relevant studies were identified using comprehensive searches across academic databases, including PubMed, Semantic Scholar, Web of Science, and Google Scholar.

A targeted search strategy was developed around key concepts such as demographic diversity, interdisciplinary collaboration, international doctoral cohorts, and their effects on research innovation. Initial searches yielded over 1,000 potentially relevant publications. After the removal of duplicates, approximately 700 articles were screened based on titles and abstracts for relevance to the specific research questions. From these, over 500 full-text articles were assessed for eligibility using criteria that included clarity of methodology, robustness of results, sample size, and direct relevance to diversity impacts in doctoral education contexts.

Ultimately, 50 peer-reviewed papers meeting the inclusion criteria were selected for detailed analysis. These papers represented a range of methodological approaches, including quantitative studies, meta-analyses, qualitative case studies, and theoretical frameworks. This diverse selection allowed for robust synthesis and a comprehensive overview of the topic, ensuring high-quality evidence formed the basis of the review’s findings and conclusions.

3. Results

3.1 Attributes of the Included Papers

The included studies span a range of methodologies, including large-scale quantitative analyses of doctoral cohorts (Hofstra et al., 2019; Yang et al., 2022; AlShebli, Rahwan and Woon, 2018), meta-analyses (Wang et al., 2019), case studies of interdisciplinary programs (Carr, Loucks and Blöschl, 2018; Trechsel et al., 2021), and theoretical frameworks (Nielsen, Bloch and Schiebinger, 2018; Salazar et al., 2012). Populations studied include US and international doctoral students, early-career researchers, and research teams across STEM and social science disciplines. Diversity dimensions examined include gender, ethnicity, nationality, academic background, and interdisciplinarity.

3.2 Main Findings: Diversity and Research Innovation

• Demographic Diversity: Underrepresented groups (by gender and race) in doctoral cohorts and research teams produce more novel and creative scientific contributions, though these are often less recognised or rewarded (Hofstra et al., 2019; McCartney, 2020; Hofstra et al., 2019; Yang et al., 2022; AlShebli, Rahwan and Woon, 2018; Gibbs et al., 2016).
• Gender Diversity: Gender-diverse teams consistently generate more novel and higher-impact research outputs, with performance advantages increasing with greater gender balance (Yang et al., 2022; Nielsen et al., 2017; Nielsen, Bloch and Schiebinger, 2018; Xie et al., 2020; Menter, 2020).
• Ethnic and International Diversity: Ethnic and international diversity are strongly correlated with higher research impact, as measured by citations and innovation metrics (AlShebli, Rahwan and Woon, 2018; Stuen, Mobarak and Maskus, 2010; Naik et al., 2022; Trechsel et al., 2021).
• Interdisciplinary Diversity: Teams and cohorts with diverse academic backgrounds and disciplines demonstrate enhanced creativity, originality, and the ability to integrate new knowledge (Liu et al., 2025; Carr, Loucks and Blöschl, 2018; Specht and Crowston, 2022; Salazar et al., 2012).

3.3 Moderators and Mechanisms

• Inclusion and Integration: The benefits of diversity are maximised in environments that foster inclusion, effective team integration, and supportive mentorship (Smolock and Robert, 2020; Puritty et al., 2017; Olzmann, 2020; Risner et al., 2020).
• Barriers and Paradoxes: Despite higher innovation rates, underrepresented groups face systemic barriers, including bias in evaluation, limited career advancement, and undervaluation of their contributions (Hofstra et al., 2019; Hofstra et al., 2019; Gibbs et al., 2016; Puritty et al., 2017; Boghdady, 2025).
• Optimal Diversity: Some studies suggest an inverted U-shaped relationship, where moderate diversity maximises innovation, but excessive diversity without integration can introduce coordination challenges (Yegros-Yegros, Rafols and D’Este, 2015; Wang, Gan and Yang, 2022; Tsai, 2021).

3.4 Contrasts and Limitations

• Recognition Gap: The “diversity–innovation paradox” persists, with diverse cohorts innovating more but not always receiving proportional recognition or career rewards (Hofstra et al., 2019; Hofstra et al., 2019; Gibbs et al., 2016).
• Contextual Factors: The impact of diversity varies by context, such as discipline, team size, and institutional support (Xie et al., 2020; Specht and Crowston, 2022; Ozgen, 2021; Kim, Jang and Kim, 2025).

Key Papers

4. Discussion

The evidence overwhelmingly supports the claim that increased diversity among doctoral cohorts enhances research innovation, as measured by scientific novelty, creativity, and research impact (Hofstra et al., 2019; Yang et al., 2022; AlShebli, Rahwan and Woon, 2018; Liu et al., 2025; Specht and Crowston, 2022). The mechanisms underlying this effect include the integration of diverse perspectives, knowledge bases, and problem-solving approaches, which foster creative recombination and novel insights (Nielsen, Bloch and Schiebinger, 2018; Wang et al., 2019; Lungeanu and Contractor, 2015; Salazar et al., 2012). However, the literature also highlights persistent systemic barriers—such as bias in evaluation, lack of inclusion, and structural inequalities—that limit the full realisation and recognition of these benefits (Hofstra et al., 2019; Hofstra et al., 2019; Puritty et al., 2017; Gibbs et al., 2016; Olzmann, 2020; Boghdady, 2025). The “diversity–innovation paradox” underscores the need for academic institutions to not only increase diversity but also actively promote inclusion and equitable recognition of contributions (Hofstra et al., 2019; Hofstra et al., 2019; Puritty et al., 2017; Olzmann, 2020).

The quality of the research is high, with several large-scale, longitudinal, and meta-analytic studies providing robust evidence. However, some limitations exist, including context dependency, potential publication bias, and the need for more intervention-based research to identify best practices for fostering inclusion and maximising the benefits of diversity (Ozgen, 2021; Tsai, 2021; Boghdady, 2025). Overall, the research is important for informing policy and practice in graduate education, research team formation, and institutional diversity initiatives.

Claims and Evidence Table

5. Conclusion

In summary, the literature provides strong evidence that increased diversity among doctoral cohorts improves research innovation, though systemic barriers and lack of inclusion can limit the full realisation and recognition of these benefits. The most robust findings highlight the positive impact of demographic, disciplinary, and international diversity on scientific novelty, creativity, and research impact, while also emphasising the need for institutional change to address the diversity–innovation paradox.

5.1 Research Gaps

Despite the breadth of research, gaps remain in understanding the optimal conditions for leveraging diversity, the long-term career trajectories of diverse doctoral cohorts, and the most effective interventions for fostering inclusion and equitable recognition.

5.2 Research Gaps Matrix

5.3 Open Research Questions

Future research should focus on identifying best practices for fostering inclusion, understanding the long-term impacts of diversity on career trajectories, and developing interventions to maximise the benefits of diversity in doctoral education.

In conclusion, while increased diversity among doctoral cohorts clearly enhances research innovation, realizing its full potential requires systemic changes to promote inclusion, equitable recognition, and supportive environments.

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