ABSTRACT
Population size, age/sex distribution, and rural–urban distribution constitute several fundamental comparative static variables. International agreements or national policies can limit net sizes and catches on the seas, or the movement and control of water. Total wealth, sectoral output and rates of saving and investment are important, but are usually well covered in national development plans. Human welfare is commonly, and effectively, assessed by such measures as infant, child or maternal mortality rates. Literacy, school enrolment, or levels of education achieved are also commonly used measures, which speak both of welfare and of human capital, or the quality of the population. In countries with mixed ethnic or other social groups, it is important to include such variables as religion, language, race, or ethnicity. These indicate social definitions, or differences between people that appear important to others. Societies also vary considerably in their capacity to assimilate different groups.
