Thinking Outside the Pipeline

Study suggests Ph.D. supply isn't the problem when it comes to diversifying the professoriate.

November 18, 2016
Line graph showing model predictions for the percentage of minority Ph.D. graduates (gray), and the corresponding percentages of minority assistant professors (black), as a function of various intervention strategies to increase faculty diversity

Many faculty diversity initiatives are predicated on the pipeline theory: that getting more minority students to enroll in Ph.D. programs eventually will lead to gains in numbers of professors from underrepresented backgrounds. The pipeline theory has long had its critics, who point to other problems within the academic recruitment, hiring and retention system. A new study seeks to back up such criticisms with hard data.

First, a disclaimer from Kenneth Gibbs, the study’s lead author and a program director for the Division of Training, Workforce Development and Diversity at the National Institute of General Medical Sciences: efforts at “flooding” the pipeline are good, and having a strong pool of minority Ph.D.s is key to any diversity initiative.

“It would be an incorrect reading of these data to say those efforts are no longer important,” he said of engaging more minority students in doctoral study. “They’re necessary -- but not sufficient.”

Rather than a pipeline, Gibbs’s paper -- which does not reflect institute policy -- proposes a systems approach to the question of why diversity lags in the biomedical professoriate. Through various models, the paper suggests that there are actually more than enough new Ph.D.s to help diversify the faculty but, for various reasons, they’re not becoming and staying professors.

Using Ph.D. data from the National Science Foundation’s Survey of Earned Doctorates and faculty rosters from the Association of American Medical Colleges, researchers found that the number of Ph.D. graduates from underrepresented backgrounds (black, Hispanic and Native American), increased by a factor of 9.3 from 1980-2013.

Graduates from well-represented groups (whites, Asians and international students), by contrast, increased by a factor of 2.6.

One might expect to see gains in faculty hiring over the same period roughly equivalent to gains in Ph.D. graduates. And the researchers did -- but only for well-represented groups: they were hired as new faculty members in medical school basic science departments at a rate that strongly correlated with numbers of graduates.

Hiring of junior faculty members from underrepresented backgrounds to medical school basic science departments, however, was not related to the number of Ph.D.s.

Without intervention, that’s likely to continue, according to the paper. In 2014, for example, 5.8 percent of assistant professors in basic science departments were from underrepresented backgrounds. Based on current trends, even increasing the size of the talent pool or numbers of assistant professor positions available is not likely to increase faculty diversity; by 2030, 13.8 percent of biomedical Ph.D.s will be underrepresented minorities, while just 5.9 percent of assistant professors in basic science departments will be.

Put another way, a model in the study predicted that growing the minority Ph.D. pool 53 percent above current levels (13.8 percent versus the current 9 percent) would result in a less than 2 percent increase in the representation of minority assistant professors.

The researchers built a conceptual system dynamic model based on the data that explained 79 percent of the variance in hiring of assistant professors, without assuming any discrimination in hiring. Simulations suggested that faculty diversity would not increase significantly through the year 2080 even if there was exponential growth in the population of Ph.D. candidates from underrepresented groups.

Diversity in faculty hiring only increased as more postdoctoral candidates from underrepresented minority backgrounds transitioned onto the market and were hired.

“Decoupling of the Minority Ph.D. Talent Pool and Assistant Professor Hiring in Medical School Basic Science Departments” was published this week in eLife. It says that from 2005-13, 5,824 biomedical Ph.D.s were awarded to underrepresented minorities. But in 2014 there were actually six fewer minority professors than in 2005, despite an 8 percent growth in the overall population of assistant professors.

Analysis shows, however, that junior faculty diversity could reach parity with the pool of Ph.D. graduates -- which is estimated to grow to 10 percent underrepresented minority this year -- by hiring around 100 minority assistant professors each year for the next six years.

So, if about two-thirds of medical schools hired and retained one faculty member from any underrepresented group annually for about a tenure cycle, the proportion of junior faculty that are underrepresented minorities would be about even to the candidate pool.

Gibbs stressed that the paper is not about or advocating “quotas” in terms of minority hiring. Rather, he said, it seeks to reframe discussions about advancing faculty diversity in the interest of scientific excellence.

If the pipeline theory is incomplete, why does it persist? Gibbs said that it was probably appropriate in the mid-20th century, when faculty diversity emerged as a priority and many fields did lack diversity in their Ph.D. pools -- and "metaphors die hard.” Going forward, he said, a systems-based approach will better serve the academy.

Gibbs said he believed his approach was translatable to other disciplines struggling with faculty diversity. And why do the biomedical and other sciences continue to struggle, if not for a lack of potential candidates? Gibbs’s paper is purposely short on the why, but it does name a few usual suspects, such as hiring practices and support for these faculty members once hired.

“Faculty diversity efforts that rely primarily on enhancing rates of Ph.D. graduates (i.e., ‘filling the pipeline’) can only have their desired impact if they are coupled with efforts to get these candidates on the market and hired,” the study says. “This would require making faculty positions and work environments attractive and supportive to these scientists, ensuring the proper types of support (e.g. funding, mentorship and sponsorship) to allow [underrepresented minority] postdocs to effectively progress to independence, and ensuring institutional faculty recruitment, evaluation and retention processes support scientists from all backgrounds.”

Such efforts would have to take into account “factors such as the broader landscape in which scientists from all backgrounds have greater career options, and the specific career development of women from [minority] backgrounds who make up the majority of [minority] biomedical Ph.D. graduates,” the paper notes.

Gibbs -- noting that all jobs for Ph.D.s are good jobs, not just those in the academy -- said his paper was primarily about encouraging people to move beyond anecdotes about faculty diversity and look at the data. The study “clearly and quantitatively shows that there are thousands of Ph.D. scientists of color available now, and if the scientific community focused on actually tapping into this talent pool, we could make a major step forward in the area of faculty diversity.”


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