CHIlD LABOR IN VIETNAM: THE RELATIVE IMPORTANCE OF POVERTY. RETURNS TO EDUCATION. LABOR MOB ILTTY. AND CREDIT CONSTRAINTS A Model of Tiebout Sorting on Exogenous Community Attributes In this section, I build a formal model of the Tiebout sorting process described above. As my interest is in the demand side of the market under full information, I treat the distribution of school effectiveness as exogenous and known to all market I demonstrate that Tiebout equilibrium must be stratified as much as the market structure allows: Wealthy families always attend schools that are preferred to those attended by lowincome families