an analogous formula applies to healthเช่นการแก้ไขปัญหาด้านโภชนาการ ,with direct and indirect cost of resources devoted to health compared with the extra income gained in the future as a result of higher health status. รูป 8.2 provides a schematic representation of the trade-offs involved in the decision to continue in school.it is assumed that the individual works from the time he or she finishes school until he or she is unable to work