The bachelor's to Ph.D. STEM pipeline no longer leaks more women than men: a 30-year analysis

Abstract

For decades, research and public discourse about gender and science have often assumed that women are more likely than men to "leak" from the science pipeline at multiple points after entering college. We used retrospective longitudinal methods to investigate how accurately this "leaky pipeline" metaphor has described the bachelor's to Ph.D. transition in science, technology, engineering, and mathematics (STEM) fields in the U.S. since the 1970s. Among STEM bachelor's degree earners in the 1970s and 1980s, women were less likely than men to later earn a STEM Ph.D. However, this gender difference closed in the 1990s. Qualitatively similar trends were found across STEM disciplines. The leaky pipeline metaphor therefore partially explains historical gender differences in the U.S., but no longer describes current gender differences in the bachelor's to Ph.D. transition in STEM. The results help constrain theories about women's underrepresentation in STEM. Overall, these results point to the need to understand gender differences at the bachelor's level and below to understand women's representation in STEM at the Ph.D. level and above. Consistent with trends at the bachelor's level, women's representation at the Ph.D. level has been recently declining for the first time in over 40 years.

Keywords: STEM education; STEM persistence; doctoral education; gender differences; retrospective methods.

FIGURE 1

Bachelor’s to Ph.D. STEM persistence rates by gender and bachelor’s degree cohort (excluding life and social science). Rates especially for the last cohort (1996–2000) should be interpreted cautiously because a non-trivial proportion of students may earn Ph.D.’s in the future. Source: 2010 National Survey of College Graduates and 2010 Survey of Doctoral Recipients.

FIGURE 2

Disaggregated bachelor’s to Ph.D. STEM persistence rates by gender and bachelor’s degree cohort. Rates especially for the last cohort (1996–2000) should be interpreted cautiously because a non-trivial proportion of students may earn Ph.D.’s in the future. Source: 2010 National Survey of College Graduates and 2010 Survey of Doctoral Recipients.

FIGURE 3

Bachelor’s to Ph.D. STEM persistence rates by gender and bachelor’s degree cohort awarded (excluding life and social science), holding constant the length of time after the first bachelor’s degree. For instance, rates for the 1996–2000 cohort were based on Ph.D.s earned by 2010, rates for the 1991–1995 cohort were based on Ph.D.s earned by 2005, rates for the 1986–1990 cohort were based on Ph.D.s earned by 2000, and so on. Source: 2010 National Survey of College Graduates and 2010 Survey of Doctoral Recipients.

FIGURE 4

Women’s representation among STEM bachelor’s and Ph.D. degree earners by year of degree awarded (excluding life and social science). Ph.D. data after 2012 are not available. Source: WebCASPAR Integrated Science and Engineering Resource Data System (2014).

FIGURE 5

Screenshots from a Twitter conversation regarding the “leaky STEM pipeline,” initiated by user biochembelle on 26 August 2013. For further discussion, see http://biochembelle.com/2013/08/28/the-pipeline-isnt-leaky/. Twitter usernames are shown only for users who gave explicit permission.