Scholars from diverse fields have long proposed that interlocking factors such as cognitive abilities, discrimination and interests may cause more women than men to leave the science, technology, engineering and mathematics (STEM) pipeline after entering college.

 

Now a new Northwestern University analysis has poked holes in the much referenced “leaky pipeline” metaphor.


The research shows that the bachelor’s-to-Ph.D. pipeline in science and engineering fields no longer leaks more women than men as it did in the past.


The researchers used data from two large nationally representative research samples to reconstruct a 30-year portrait of how bachelor’s-to-Ph.D. persistence rates for men and women have changed in the United States since the 1970s. For this study, the term STEM persistence rate refers to the proportion of students who earned a Ph.D. in a particular STEM field (e.g. engineering) among students who had earlier received bachelor’s degrees in that same field.


They were particularly surprised that the gender persistence gap completely closed in pSTEM fields (physical science, technology, engineering and mathematics) — the fields in which women are most underrepresented.


Among students earning pSTEM bachelor’s degrees in the 1970s, men were 1.6 to 1.7 times as likely as women to later earn a pSTEM Ph.D. However, this gap completely closed by the 1990s.


Men still outnumber women by approximately three to one among pSTEM Ph.D. earners. But those differences in representation are not explained by differences in persistence from the bachelor’s to Ph.D. degree, said David Miller, an advanced doctoral student in psychology at Northwestern and lead author of the study.


“Our analysis shows that women are overcoming any potential gender biases that may exist in graduate school or undergraduate mentoring about pursing graduate school,” Miller said. “In fact, the percentage of women among pSTEM degree earners is now higher at the Ph.D. level than at the bachelor’s, 27 percent versus 25 percent.”


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