Preferences, Identity, and Competition: Predicting Tie Strength from Demographic Data

This research examines the combined influence of three causal mechanisms shaping interpersonal dynamics. Sharing a demographic characteristic has been shown to strengthen a relationship between people. The initial explanation for this positive effect emphasized the importance of individual preferences for social contact. Similar people share common interests, which makes them more attractive as exchange partners. More recent explanations have highlighted the important role of identification and competition. Identification increases the tendency for strong ties to develop among similar people, while competition reduces that tendency. I argue that tie strength is a function of all three mechanisms: a baseline level of interpersonal attraction, a positive identification effect, and a negative competition adjustment. Identification and competition vary with the number of people sharing the focal attribute to define a predictable association between sharing the focal attribute and the strength of a network connection. Predictions are tested with tenure and tie-strength data from a small research and development firm. Analysis indicates that having the same tenure has the predicted effect on communication frequency. The implications of the findings are discussed for homophily research in particular and demography research in general.