ABSTRACT
Endogenous growth models assume dynamic learning processes in which the output of a given firm depends on the lagged value of aggregate industry output. Biological models of contagion suppose that the probability of an uninfected person becoming infected varies with the fraction of the population already infected. This chapter utilizes the term anonymous endogenous interactions to describe the class of social processes in which the behavior of an individual varies with the distribution of behavior in a group containing the individual. The interactions are endogenous because the outcome of each group member varies with the outcomes of the other group members, not with other attributes of the group. The chapter describes some models that illustrate alternative forms of the response function. These models express a range of ideas about the nature of interactions, yet all are quite simple.
