The single most important determinant of the level of health within a community is its degree of poverty. Poverty can be defined as the lack of adequate disposable income to met the basic needs of a person. Poverty is usually defined a household income of less than half of the median household income in a community. However, this is relative. In Hong kong this poverty value is around HK$2,500 p.m. In Afghanistan, the value will be much lower because the median level of wealth is much less.

One important factor to be important in determining health is relative wealth. Even in countries, like Hong Kong, which have high per capita income, those with the most wealth have better health overall than those with somewhat less wealth but still materially very comfortable. In poor societies, the slightly better off have better health than the slightly worse off. This wealth-related, relative health effect has been shown in terms of the positive correlation between the sizes of dowries (wedding payments) given by Florentine people in 14th Century Italy, upon marriages of their daughters with the daughter’s subsequent age of death (those giving larger dowries lived longer); between the size of tombstones in 19th Century Scottish churchyards (a proxy measure of wealth) and the age at death inscribed upon the tombstones (those who could afford larger tombstones dies at a greater age), and the rapid and substantial decline in life-expectancy by about 8-10 years among Russian males since the collapse of Communism, and particularly since the economic collapse of Russia.