The leaky pipeline of diverse race and ethnicity representation in academic science and technology training in the United States, 2003–2019

Introduction Diverse race and ethnicity representation remains lacking in science and technology (S&T) careers in the United States (US). Due to systematic barriers across S&T training stages, there may be sequential loss of diverse representation leading to low representation, often conceptualized as a leaky pipeline. We aimed to quantify the contemporary leaky pipeline of S&T training in the US. Methods We analyzed US S&T degree data, stratified by sex and then by race or ethnicity, obtained from survey data the National Science Foundation and the National Center for Science and Engineering Statistics. We assessed changes in race and ethnicity representation in 2019 at two major S&T transition points: bachelor to doctorate degrees (2003–2019) and doctorate degrees to postdoctoral positions (2010–2019). We quantified representation changes at each point as the ratio of representation in the later stage to earlier stage (representation ratio [RR]). We assessed secular trends in the representation ratio through univariate linear regression. Results For 2019, the survey data included for bachelor degrees, 12,714,921 men and 10.612,879 women; for doctorate degrees 14,259 men and 12,860 women; and for postdoctoral data, 11,361 men and 8.672 women. In 2019, we observed that Black, Asian, and Hispanic women had comparable loss of representation among women in the bachelor to doctorate transition (RR 0.86, 95% confidence interval [CI] 0.81–0.92; RR 0.85, 95% CI 0.81–0.89; and RR 0.82, 95% CI 0.77–0.87, respectively), while among men, Black and Asian men had the greatest loss of representation (Black men RR 0.72, 95% CI 0.66–0.78; Asian men RR 0.73, 95% CI 0.70–0.77)]. We observed that Black men (RR 0.60, 95% CI 0.51–0.69) and Black women (RR 0.56, 95% CI 0.49–0.63) experienced the greatest loss of representation among men and women, respectively, in the doctorate to postdoctoral transition. Black women had a statistically significant decrease in their representation ratio in the doctorate to postdoctoral transition from 2010 to 2019 (p-trend = 0.02). Conclusion We quantified diverse race and ethnicity representation in contemporary US S&T training and found that Black men and women experienced the most consistent loss in representation across the S&T training pipeline. Findings should spur efforts to mitigate the structural racism and systemic barriers underpinning such disparities.


Introduction
Diverse race and ethnicity representation remains lacking in science and technology (S&T) careers in the United States (US). Due to systematic barriers across S&T training stages, there may be sequential loss of diverse representation leading to low representation, often conceptualized as a leaky pipeline. We aimed to quantify the contemporary leaky pipeline of S&T training in the US.

Methods
We analyzed US S&T degree data, stratified by sex and then by race or ethnicity, obtained from survey data the National Science Foundation and the National Center for Science and Engineering Statistics. We assessed changes in race and ethnicity representation in 2019 at two major S&T transition points: bachelor to doctorate degrees (2003-2019) and doctorate degrees to postdoctoral positions (2010-2019). We quantified representation changes at each point as the ratio of representation in the later stage to earlier stage (representation ratio [RR]). We assessed secular trends in the representation ratio through univariate linear regression.  [4]. The "leaky pipeline" framework conceptualizes low representation based on "leaks" due to systemic barriers across the education and training continuum [1]. Prior work using data from 2000 to 2013 assessed the journey of Black, Hispanic, and AI/ AN populations across the training pathway from high school to research faculty positions in the biomedical sciences in the US, finding losses of representation mainly during undergraduate studies, with otherwise minimal losses of attrition in the receipt of a doctorate degree or receipt of a postdoctoral position [3]. Updated trends in representation since 2013, aggregated trends across S&T fields, trends by sex, as well as representation of Asian populations who represent one of the fastest growing groups in the US, remain incompletely understood. To address these gaps, we sought to quantify the contemporary leaky pipeline of US S&T training by race and ethnicity groups across three major training stages: undergraduate (bachelor) degrees, doctorate degrees, and postdoctoral positions.

Methods
We obtained cross-sectional 2003-2019 S&T (which included all reported science and engineering fields) degree data from the National Science Foundation and the National Center for Science and Engineering Statistics which was comprised of findings from the National Survey of College Graduates, the Survey of Doctorate Recipients, and the Survey of Graduate Students and Postdoctorates in Science and Engineering (2010-2019). Race and ethnicity groups were included based on available data: Non-Hispanic White (NHW), Non-Hispanic Black (Black), Non-Hispanic Asian (Asian), Hispanic or Latino (Hispanic), and Non-Hispanic AI/AN. In NCSES survey data, those classified as Hispanic or Latino may be of any race, while those categorized as a race exclude those of Hispanic ethnicity. Temporary visa holders were excluded from the analysis because their race or ethnicity data are not reported. We calculated race or ethnicity group representation (%) separately for men and women and evaluated two transition points: bachelor to doctorate degree receipt, and doctorate degree receipt to postdoctoral positions. We quantified differences in representation at each transition as the ratio of representation in the subsequent stage to that of the previous stage in the same year. A representation ratio less than 1 indicated loss of representation across that transition point. We calculated 95% confidence intervals (CIs) for the representation ratios in the standard manner as for risk ratios. AI/AN data were excluded due to very low sample sizes (for example, N<50 for doctoral data) with consequent limited interpretability and reliability. We assessed trends over time in representation ratios using univariate linear regression. A p-trend threshold of 0.05 denoted statistical significance. R, version 4.0.0, was used for statistical analyses.

Doctorate to postdoctoral transition
In 2019, among women, Black women demonstrated the greatest loss of representation (ratio 0.56, 95% CI 0.49-0.63, Fig 1E). Among men, Black men demonstrated the greatest loss of representation (ratio 0.60, 95% CI 0.51-0.69, Fig 1F). From 2010 to 2019, NHW women had a small increase in the representation ratio (p = 0.007), while Black women experienced a small decrease (p = 0.02), with no statistically significant trends for other groups among men or women (all p > 0.05, Fig 1E and 1F).

Discussion
Black men and women experienced the most consistent losses in representation across the aggregated contemporary US S&T training pipeline from bachelor degrees to postdoctoral positions. The leaky aggregated S&T pipeline has largely remained unchanged across diverse race and ethnicity groups in men and women from 2003 to 2019, with Black women experiencing a possibly small decrease in representation in the transition from doctoral degree receipt to postdoctoral positions.
As race and ethnicity generally represent sociocultural constructs, observed disparities likely reflect structural racism and barriers. Prior work suggested that in the biomedical sciences, from 2000 to 2013, loss of representation in underrepresented minority (URM) groups defined as Black, Hispanic, and AI/AN groups was minimal in the receipt of doctoral degrees and the receipt of a postdoctoral position within the biomedical sciences [3]. Our data from a more recent period at an aggregated S&T level suggest losses of representation across these transitions in certain groups when disaggregated by sex. Additionally, our analysis utilizes a simple, intuitive variable-the representation ratio-to quantify "leaks" in the training pipeline (that is, loss of representation at each stage of transition) and demonstrate that this variable can potentially be tracked over time to quantify progress or lack of progress in improving the leaky pipeline. Efforts are needed to further explore and validate these findings and address the biases underpinning the leaky S&T pipeline.
This analysis does not capture other transitions including high school to undergraduate or postdoctoral to faculty. The pipeline concept does not incorporate all S&T careers; for instance, postdoctoral training may not be relevant to non-tenure track academic or industry positions, or entrepreneurial careers. Heterogeneity by disaggregated groups or disaggregated fields of study was not captured in these data. Higher Asian representation may reflect decreasing representation in other groups and should be interpreted with caution. Those on temporary visas were not captured in this analysis. These data aim to explore longitudinal trends using serial cross-sectional survey data and should be interpreted within these limitations.
In conclusion, Black men and women experienced the greatest representation losses across the aggregated US S&T training pipeline from bachelor degrees to postdoctoral positions with no significant evidence of improvement over a contemporary time period.