Dive Brief:

• Community colleges rely heavily on adjunct professors, but new research suggests that the part-time instructors may adversely affect student performance at two-year institutions, particularly in STEM and health field courses.
• Research conducted by Di Xu, an assistant professor of educational policy at the University of California, Irvine, shows that while students having an adjunct instructor got better grades in introductory courses, they were more likely to drop subsequent courses in the field of study or get, on average, 4% lower grades than if they were instructed by a full-time faculty member.
• The research notes that the use of adjuncts is greatest at community colleges, which play "a critical role in addressing the national equity agenda by disproportionately serving underrepresented groups."

Dive Insight:

In another study co-authored by Xu, she suggests the negative effect on students is stronger when extra faculty members are hired temporarily than with adjuncts who have long-term employment contracts with a college. In a related working paper, she said the differences can be largely explained by "key instructor demographic and employment characteristics, including highest degree attained, whether employed full-time in the college, and whether [they] had previous work experience in non-teaching positions." 

While part-time faculty members who also work in business and industry bring expertise and insights to the classroom, they typically are less available to interact with students outside of class. Some experts also say that students who take more courses from adjunct faculty members are less likely to graduate or transfer, while research shows that there are positive educational outcomes from taking courses from full-time professors, including higher grades and retention.  

The National Center for Education Statistics has reported that the number of full-time faculty members increased by about 7% in the five years ending in 2016, while part-time faculty members decreased by about 4% during that period after a 74% rise over the previous dozen years, perhaps because as institutions trim expenses, adjuncts are the first instructors to be let go.