The socioeconomic performance of today's workers depends not only on parental skills, but also on the average skills of the ethnic group in the parents' generation (or ethnic capital). This paper investigates the link between the ethnic externality and ethnic neighborhoods. The evidence indicates that residential segregation and the external effect of ethnicity are linked, partly because ethnic capital summarizes the socioeconomic background of the neighborhood where the children were raised. Ethnicity has an external effect, even among persons who grow up in the same neighborhood, when children are exposed frequently to persons who share the same ethnic background.

Experimental evidence shows that an important reason why people tend to imitate others, to exhibit "herd behavior" is that they assume that the others have information that justifies their actions. The information cascade models of Banerjee [1992] and Bikhchandani et al. [1992] are significant developments in showing some general equilibrium and welfare effects of such rational imitative behavior. But these models as specified may be of limited applicability since they assert that differences across groups in herd behavior can be attributed to the random decisions of first movers. Differences across groups in herd behavior might be explained more often in terms of different modes of interpersonal information transmission. Patterns of human conversation imply great selectivity to the kinds of information transmitted within groups.

The norming of the third edition of the Test of Understanding College Economics (TUCE III) has produced a valuable data set (Phillip Saunders, 1994). These data describe 93 introductory macro and 96 introductory microeconomics classes taught by 131 different instructors at 53 U.S. colleges and universities in 1989-1990. It is tempting to use this sample to investigate how class size influences learning. The nonexperimental nature of the data, however, raises the possibility of an endogeneity problem: department chairs may assign better teachers to larger classes, and those teachers, in turn, may attract even greater numbers of students. Teaching quality, therefore, may be higher in larger classes. Thus, the discovery from these data of any deleterious effect on learning from larger classes may be only a lower bound. The education literature, admirably surveyed by Wilbert J. McKeachie (1990), suggests that learning is not much affected by class size. One reason for this result may be that instructors do not adjust their teaching methods to class size. In this paper we use the TUCE III data to examine whether introductory economics instructors vary pedagogy with class size. I. The Role of Instructor Behavior

We provide a framework within which the child-support compliance decisions of noncustodial fathers and the child-support awards set by institutional agents can be coherently interpreted. The model of child-support transfers is able to capture qualitatively the features of the monthly payment distribution. Estimated parental-decision rules are used to infer the implicit weights given by institutional agents to the postdivorce welfare of parents and children. We find that the weight attached to the combined welfare of the custodial mother and child is significantly less than the weight given to the father's welfare in most sample cases.