Truck and Barter: Fascinating New Paper

May 24, 2005

Fascinating New Paper

By Ian

From the NBER emails on new working papers I found reference to a new paper by Echenique and Fryer: "On The Measurement of Segregation."

ABSTRACT: This paper develops a measure of segregation based on two premises: (1) a measure of segregation should disaggregate to the level of individuals, and (2) an individual is more segregated the more segregated are the agents with whom she interacts. Developing three desirable axioms that any segregation measure should satisfy, we prove that one and only one segregation index satisfies our three axioms, and the two aims mentioned above; which we coin the Spectral Segregation Index. We apply the index to two well-studied social phenomena: residential and school segregation. We calculate the extent of residential segregation across major US cities using data from the 2000 US Census. The correlation between the Spectral index and the commonly-used dissimilarity index is .42. Using detailed data on friendship networks, available in the National Longitudinal Study of Adolescent Health, we calculate the prevalence of within-school racial segregation. The results suggests that the percent of minority students within a school, commonly used as a substitute for a measure of in-school segregation, is a poor proxy for social interactions.

A previous copy of the paper can be found here in PDF.

The whole thing is packed with fascinating ideas stemming in part from the model's disaggregation from the city level to the individual. Particularly fascinating was the ability of the new model (the SSI) to distinguish well between "mechanical" and "behavioral" segregation (that is, the amount of segregation one would expect based on the actual distribution of races versus the purposeful segregation evinced through choice of separatign oneself from a non-similar race) that illustrates a number of compelling such as:

Interestingly, one learns from Table 7 [a table describing "the SSI of the most segregated connected components by size of the component."] that blacks are more segregated than any other racial group, but the most segregated Hispanics are more segregated than the most segregated Blacks. Table 8 provides the top 15 most segregated blocks in America. A Hispanic block in San Antonio is the most segregated block, followed by a Black block in Lafayette, LA and an Asian block in Los Angeles

From the sections on school segregation:

Many researchers assume the relationship [between the percentage of minority students in a school and the level of segregation for each minority student in that school] is linear (see, for example, Orfield 1983). This seems to be true for Whites, Asians, and to a lesser extent Hispanics. For Blacks, however, the relationship between percent own-race in a school and own-race segregation is highly non-linear. As the percentage of black students increases from zero to twenty-five percent, black segregation rises sharply. Above twenty-five percent, Blacks are near complete segregation.

Posted at May 24, 2005 06:00 PM

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