Polycentric population density functions are becoming increasingly popular among urban economists who claim that monocentric functions are inadequate for analyzing population distribution of contemporary, relatively dispersed urban areas. Unfortunately, none of the studies which appeared has been successful in generating a theoretical model amenable to straightforward empirical application. It is even unclear what the relationship is between a polycentric function and the individual functions derived for each center. In this paper we estimate monocentric and duocentric density functions using census tract data for Jerusalem. The somewhat simplified urban structure of this city, which contains two almost completely economically and politically segregated populations, each interacting with its separate central business district (CBD), appears to be advantageous in uncovering the relationships between the monocentric and duocentric functions. The findings of the analysis provide support for the duocentric formulation employed. Whereas the qualitative and quantitative results of the duocentric estimates are similar to those derived with the monocentric model, the best statistical fit of the data is obtained with the duocentric model. These findings enhance the credibility of the duocentric model, because compatibility is expected when dealing with two almost completely segregated populations. Further support is obtained when the model is estimated jointly with the location of the two CBDs. The estimates of the locations of the two CBDs are found to be extremely accurate. This is true for both the monocentric and duocentric regressions.
- Duocentric city
- Polycentric urban structure
- Population density
- Urban structure with two unknown CBDs