Social epidemiology is the study of the biological basis of disease. the availability of doctors around the world. the age at which people die. the distribution of health and illness in a population.

In financial aspects, a depression is a sustained, long haul downturn in monetary movement in one or more economies. it is a more extreme monetary downturn than a recession, which is a slowdown in financial action through the span of a typical business cycle. a depression is an irregular and extreme type of recession. so depression is always followed by recession but it is not correct to state that a depression always follow a recession.