Block, Tract, and Levels of Aggregation: Neighborhood Structure and Crime and Disorder as a Case in Point

es on how structural characteristics affect various outcomes. One form of this research tests whether structural characteristics of neighborhoods affect various aggregate outcomes, such as crime, economic vibrancy, cohesion, or even death from heat waves (Browning et al. 2006). Another form of this research employs multilevel models to test whether the structural or cultural characteristics of neighborhoods affect various individual-level outcomes, such as educational achievement, psychological wellbeing, or residential satisfaction. Despite the variety of research paradigms focusing on the importance of neighborhoods, a commonality of many studies is that less attention is paid to the appropriate level of aggregation for such neighborhood effects. Consequently, whereas a shared knowledge suggests that the size of such neighborhood effects is relatively small compared to individual-level effects (Liska 1990), it is possible that misspecification of the proper level of aggregation for such effects might partially explain these smaller than expected contextual effects. The importance of considering the level of aggregation is not new and is the basis of the modif iable areal unit problem (MAUP) (Openshaw and Taylor 1979, 1981). The MAUP occurs when aggregating processes that are not homogenous over the geographic area (Anselin Block, Tract, and Levels of Aggregation: Neighborhood Structure and Crime and Disorder as a Case in Point