Do "Weed-Out" Courses Weed Students Out? The Impact of Calculus I on STEM Persistence

• In Event: Policies and Interventions for Student Persistence in STEM Fields

Abstract

Introduction: Large introductory college courses in science, technology, engineering, and mathematics (STEM) fields are key entry points into STEM majors. But some studies have identified introductory courses as “weed-out courses” that are barriers to persistence in STEM majors, particularly for women and students from other backgrounds underrepresented in STEM (Gasiewski et al. 2012; Seymour and Hewitt 1997; Weston et al. 2019). This dynamic may contribute to patterns of unequal attrition from STEM fields, where gender disparities are especially stark in fields like physical science, engineering, mathematics, and computer science (PEMC) (Dika and D’Amico 2016; Perez-Felkner et al. 2012). In particular, research has pointed to Calculus I as a culprit in gendered attrition from STEM (Ellis, Fosdick, and Rasmussen 2016; Sanabria and Penner 2017). Purpose: Little research has systematically established the impact of an introductory course apart from differences in students’ background characteristics or academic ability, which produces a lack of clarity in the literature about whether course attributes or student attributes are driving effects on persistence. This paper examines the following questions: 1. What effect does taking Calculus I have on students’ STEM persistence outcomes? 2. Does this effect differ by gender? and 3. What aspects of the course or the students account for these differences? Design: In this paper, I use a difference-in-differences design to examine a change in curriculum policy at a single large, highly selective university in the Midwestern United States. The policy change induced students who had not previously been required to take Calculus I to take the course. This quasi-experimental design allows me to disentangle the impact of the course from those of students’ characteristics, clarifying whether the course contributes to STEM attrition. I use the university’s administrative data, which include student records and academic transcripts. My sample includes the 2008 through 2019 entering cohorts of first-time bachelor’s degree-seeking undergraduates in the university’s Arts and Sciences College who earned a 4 or 5 on AP Calculus AB or BC (N=17,280). Results: I find that the policy change induced a large (34 percent) increase in taking Calculus I but reduced students’ chances of taking Calculus II, the next course in the sequence. Furthermore, it decreased students’ chances of declaring and graduating with physical science, engineering, mathematics, and computer science majors requiring Calculus by about 4 percent. In contrast, it slightly increased students’ chances of declaring and graduating with biological sciences majors by 2 percent. While similar patterns were apparent for both men and women, they were stronger and statistically significant for women. Preliminary analyses examining course-related mechanisms for the decrease in physical science graduation suggest that earning a failing grade and having a lower percentage of same-gender peers in Calculus may contribute. These results suggest that Calculus I acts as a barrier to physical sciences degrees at this institution, shifting students out of physical sciences majors into biological sciences majors. This is especially true for women. Thus, even for high-achieving STEM students, introductory courses like Calculus may serve a “weed-out” function, rather than promoting persistence.

Author

• Katherine Leu, University of Michigan Ann Arbor
  Presenting Author