Mobility may be inter-generational or intra-generational. When mobility between generations it is termed inter-generational. When mobility is within a person or groups lifetime it is termed intra-generational. Again mobility may be absolute or relative. Absolute mobility involves widespread economic growth and upward economic mobility of families over a generation. Relative mobility is a zero-sum game, absolute is not. Inter-generational mobility compares a persons or group's income to that of parents. Intra-generational mobility refers to movement which may be up or down during the course of a career. Relative mobility is specific to individuals or groups and occurs without relation to the economy. Relative mobility is about how closely the economic fortunes of children relate to that of their parents.
We also have social mobility of people between one social class or economic level, like vertical social mobility, horizontal social mobility and contest mobility.
According to the 2007 "American Dream Report" study, relative mobility between generations, America is a less mobile society than many other nations, including Canada, France, Germany and most Scandinavian countries and this challenges the notion of America as the land of opportunity. Some research places the U.S. among the least economically mobile countries. "Economic Mobility Project: Across Generations", a 2007 study found significant upward "absolute" mobility from the late 1960s to 2007, during which period two-thirds of those who were children in 1968 reporting more household income than their parents. Contrary to American beliefs about equality of opportunity, a childs economic position is influenced by that of his or her parents. Only half of the generation studied exceeded their parents economic standing by moving up one or more quintiles.
According to a 2007 study by the US Treasury Department, Americans concerned over the recent growth in inequality can be reassured by the healthy income mobility in America: There was considerable intragenerational income mobility of individuals in the U.S. economy from 1996 through 2005 as over half of taxpayers moved to a different income quintile over this period.