McPherson is a network sociologist, Professor Emeritus at Duke and previously at the University of Arizona, whose career subject is the structure of voluntary association: who ends up connected to whom, and what that does to the flow of information. “Birds of a Feather,” written with Lynn Smith-Lovin and James M. Cook for the Annual Review of Sociology in 2001, is a review of the homophily principle.
Its use here is direct. If similarity structures ties of every kind (marriage, friendship, work, advice), then five contacts drawn from one network are not five independent readings of what great looks like; they are close to one reading repeated. That is the evidence behind the page’s instruction to sample across social clusters rather than depth-first within your own, and behind the warning that a homogeneous seed produces a confident but narrow standard. He is a sociologist whose work is borrowed into management, not a management researcher.