As CS Enrollments Grow, Are We Attracting Weaker Students?

In recent years, enrollments in undergraduate computer science programs have seen tremendous growth nationally. Often accompanying such growth is a concern from faculty that the additional students choosing to pursue computing may not have the same aptitude for the subject as was seen in prior student populations. Thus such students may exhibit weaker performance in computing courses. To help address this question, we present a statistical analysis using mixture modeling of students' performance in an introductory programming class at Stanford University over an eight year period, during which enrollments in the course more than doubled. Importantly, in this setting many variables that would normally confound such a study are directly controlled for. We find that the distribution of student performance during this period, as reflected in their programming assignment scores, remains remarkably stable despite the large growth in enrollment. We then explain how the notion of having "more weak students" and the fact that the distribution of student ability is unchanged can readily co-exist and lead to misperceptions about the quality of incoming students during an enrollment boom.