Diversity trends among faculty in STEM and non-STEM fields at selective public universities in the U.S. from 2016 to 2023

The racial and gender diversity of university faculty has been a long-standing concern for researchers and policymakers. Advocates highlight the benefits of a diverse faculty, including enriching the curriculum, fostering student belonging, and challenging stereotypes. The 2015-2016 racial protests on college campuses spurred significant university investments in diversity, equity, and inclusion (DEI) initiatives, primarily focused on hiring practices. These initiatives, such as appointing diversity advisors to hiring committees and creating diversity-focused postdoctoral programs, aimed to improve faculty diversity, especially in STEM fields where underrepresentation of women and minorities is particularly acute. Prior research, such as Li and Koedel (2017), highlighted existing racial-ethnic and gender imbalances in faculty representation across STEM and non-STEM fields, raising concerns that untargeted DEI efforts might exacerbate these disparities. A substantial body of literature shows that student outcomes improve when they are exposed to instructors from similar demographic backgrounds. This study investigates the impact of recent DEI initiatives on faculty diversity trends, examining whether they have successfully narrowed or widened the existing gaps between STEM and non-STEM fields.

Existing research extensively documents the underrepresentation of Black, Hispanic, and female professors in academia, particularly within STEM fields. Studies like Li and Koedel (2017) and Ginther et al. (2010) have shown this imbalance stems partly from disparities in PhD attainment among these groups. The importance of demographic matching between students and instructors has been consistently demonstrated, showing positive effects on student performance, course completion, and major choices, particularly in STEM. Studies such as Bettinger and Long (2005), Carrell et al. (2010), and Fairlie et al. (2014) highlight the role of role models and the positive impact of having instructors from similar backgrounds. The existing literature sets the stage for this study's investigation into how recent university efforts to increase faculty diversity have affected the representation of different groups across STEM and non-STEM fields.

This study utilizes two primary data sources: the Integrated Postsecondary Education Data System (IPEDS) and a unique panel dataset constructed by the authors, referred to as the "L&K dataset." IPEDS data, while comprehensive and covering all U.S. universities participating in federal student aid programs, lacks information on faculty fields. The L&K dataset, built upon the dataset used by Li and Koedel (2017), addresses this limitation by providing faculty field information for a sample of 40 selective public universities, focusing on six departments: biology, chemistry, economics, English, educational leadership and policy, and sociology. The L&K dataset covers all tenured and tenure-track faculty in these departments, collected in 2015-16 and again in 2022-23. The study uses IPEDS data to document broad diversity trends from 2002-2022, focusing on the L&K university subsample for comparability. The L&K dataset allows for a detailed examination of diversity trends in STEM (biology, chemistry, economics) versus non-STEM fields. The authors employ interrupted time series (ITS) regressions to analyze whether diversity trends changed significantly after the 2016 protests, comparing post-protest trends to pre-protest trends. The analysis focuses primarily on assistant professors due to the hiring-centric nature of university DEI initiatives. The study also presents a comparative analysis of changes in faculty shares across fields and ranks from 2016 to 2022 (IPEDS) and 2023 (L&K dataset). Sensitivity analyses were conducted to assess the robustness of findings using alternative field classifications and a broader sample of public R1 universities.

The study reveals heterogeneous trends in faculty diversity across STEM and non-STEM fields since the 2015-16 academic year. Using IPEDS data, the authors find increasing diversity across all racial-ethnic and gender categories since 2002, but with varying rates of growth. While the share of White faculty has declined, the share of Asian faculty has substantially increased, while Black and Hispanic faculty representation shows less pronounced growth, although with recent, accelerating increases in assistant professor representation. The share of female faculty has steadily increased across all ranks, with the gender gap narrowing over time. The ITS regression analysis reveals that the share of Black assistant professors shows statistically significant increases post-2016 relative to the pre-protest trend, while the share of White assistant professors shows a statistically significant decrease post-2016. Comparing diversity trends in STEM and non-STEM fields from 2016 to 2023, reveals a widening racial-ethnic gap, particularly for Black faculty, as their representation increased more rapidly in non-STEM fields. In contrast, the gender gap is narrowing, with the share of female faculty increasing more substantially in STEM fields. This trend heterogeneity is particularly evident among assistant professors, reflecting the influence of university DEI initiatives focused on hiring practices. The study also finds that changes in other faculty ranks are generally smaller and less statistically significant, highlighting that the impact of university diversity initiatives extends beyond assistant professors but is most pronounced at that level.

The findings demonstrate that recent diversity efforts have had a heterogeneous impact on faculty representation across STEM and non-STEM fields. The widening racial-ethnic gap, especially for Black faculty, raises concerns about the potential reinforcement of existing underrepresentation of minority students in STEM. This is concerning because student success is linked to instructor demographic representation. Conversely, the narrowing gender gap suggests that targeted initiatives, such as the long-standing support for gender diversity in STEM through programs like NSF ADVANCE, may be more effective. The study's focus on assistant professors highlights the importance of considering the long-term effects of hiring-focused DEI strategies on the overall faculty composition across different fields. The study’s limitations include the relatively small sample size preventing detailed analysis of specific race-gender combinations and the challenge of disentangling the effects of university initiatives from broader societal changes in academia.

This study reveals complex and heterogeneous trends in faculty diversity across STEM and non-STEM fields. While some progress has been made, particularly in narrowing the gender gap, the widening racial-ethnic gap, especially for Black faculty, requires further attention. Future research should focus on more granular trends, considering specific race-gender combinations, and analyzing the correlation between faculty diversity and student outcomes across different fields. The findings underscore the importance of considering field-specific strategies in promoting faculty diversity and avoiding unintended consequences that may hinder the representation of minority students in STEM. Long-term follow-up research is crucial to fully understand the lasting impact of recent university DEI initiatives.

The study's limitations include the relatively small sample size of the L&K dataset, limiting the analysis of more granular demographic groups (e.g., Black women in STEM). Furthermore, the study's focus on specific departments within a sample of selective universities may not fully represent the diversity trends in all U.S. public universities. The inability to disentangle the effects of university-specific initiatives from broader societal and academic trends is also a limitation. Finally, the study does not directly address the causal link between faculty diversity and student outcomes, leaving this aspect for future research.