Still a Small World? University Course Enrollment Networks before and during the COVID-19 Pandemic

In normal times, the network ties that connect students on a college campus are an asset; during a pandemic, they can become a liability. Using pre-pandemic data from Cornell University, Weeden and Cornwell showed how co-enrollment in classes creates a “small world” network with high clustering, short path lengths, and multiple independent pathways connecting students. In this paper, we show how the structure of the enrollment network changed as Cornell, like many American colleges and universities, shifted to a hybrid instructional model with some courses online and others in person. Under this model, about half of students are disconnected from the in-person co-enrollment network. In this network, paths lengthened, the share of student pairs connected by three or fewer degrees of separation declined, and clustering increased, with a greater share of ties occurring between students in the same field. The small world became both less connected and more fragmented. (Corrected page proofs. Paper is forthcoming in Sociological Science.)