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Social Mobility is often measured as the chance of your children's income moving up/down from your income quintile compared to other people in the same nation.

Social mobility [...] refers to individuals or families, and their change in income (economic mobility). It also typically refers to vertical mobility—movement of individuals or groups up (or down) from one socio-economic level to another, often by changing jobs or marriage; [...] Social mobility can be the change in status between someone (or a group) and their parents/previous family generations ("inter-generational"); or over the change during one's lifetime ("intra-generational"). [...] "relative"—an estimation of the chance of upward (or downward) social mobility of a member of one social class in comparison with a member from another class. A higher level of intergenerational mobility is often considered a sign of greater fairness, or equality of opportunity, in a society.

While I have found some data regarding social mobility within a nation, I have been having difficulty in finding data regarding international social mobility. The wiki on Social Mobility notes that the USA has a lower level of social mobility than Sweden, but those studies (and others) are all measured relative to other people within the same nation.

The New York Times and the Wall Street Journal published a series of front-page articles on this issue in May 2005. Americans have often seen their country as a ‘land of opportunity’ where anyone can succeed despite his background. A study performed by economists at the Organization for Economic Cooperation and Development in 2009 found that Britain and the United States have the lowest levels of intergenerational mobility, or the highest levels of intergenerational persistence. The Nordic countries (Norway, Sweden, Denmark and Finland) and Canada tend to have high rates of social mobility. Norway proved to be the most mobile society.

To give you an example of why this matters, imagine a nation where nearly everyone makes $1 a day. Would people still consider that nation, the 'land of opportunity' because of a low level of intergenerational persistence? (i.e. If you were born into the top quintile making $2/day (or bottom quintile making $0.75/day), but your were equally likely to remain there or in one of the other quintiles (20% chance)).

For a real life example, I was able to find this income data for 2011. Table 10.1 shows Sweden and the USA Household Annual Disposable Income by Decile (pg 24)

Decile   1.     2.     3.     4.     5.     6.     7.      8.      9.     10.
Sweden|22,167|30,875|36,170|40,873|45,634|50,926|57,384| 66,273| 81,348|146,487
USA   | 8,223|20,431|31,872|43,895|57,260|72,886|92,292|118,632|160,864|300,367

What are the chances of a person born in Sweden moving from their USA income quintile/decile to another USA income quintile/decile over their lifetime? (is this more/less than the intergenerational social mobility of an American in the USA?)

(I.e. What are the chances of a Swede born into a family making $22,000 (Decile 2 USA) to end up making $160,000 (Decile 9))

  • I don't understand your example. If everybody makes $1, that that's complete intergenerational persistence. And if you then go on to make $2, that's still doubling your income. I think your example is predicated on the assumption that it's easier to increase income by a given percentage when it's lower, which I don't know is the case. In fact, given the disproportionate distribution of gains in the past several decades, I'd venture to say the opposite is true. – Avi Feb 1 '14 at 21:07
  • @Avi, what I actually wrote was, "nearly everyone" I do think it easier to move from a lower to higher quintile when the delta is smaller(I would accept that as an axiom). It would be interesting to note how easy it for an American born into a particular Swedish decile to move to another Swedish decile/quintile. That data would illustrate pretty much the same theory. (Should I expand the question to allow that?) The opposite of what is true? it's harder to increase income by a given percentage when [the difference between deciles is] lower? Moving within deciles is harder – user1873 Feb 2 '14 at 8:10
  • @user1873 What matters is not income measured in dollars, but rather income measured in dollars adjusted for purchasing power parity. After all, if you live in a country where a dollar buys a lot of goods and services, then it's worth more and is thus harder to get. – Keshav Srinivasan Feb 3 '14 at 14:52
  • @KeshavSrinivasan, not exactly. Some studies that show the USA/Sweden have a very similar absolute mobility ($US real dollars), I am interested in what those Absolute gains are with respect to relative gains on the US decile/quintile group. Some argue that the US has lower relative mobility, but that is measuring US vs US, and Swedish vs Swedish. The chart above shows major differences in deciles in absolute $. – user1873 Feb 3 '14 at 15:20
  • Social mobility is not simply measured that way, it's defined that way. This is simply what this is about. What would your measure reveal about a society? – Relaxed Jan 20 '15 at 17:56
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The graph in the Wikipedia article actually does do what you want: enter image description here

The intergenerational income elasticity is a measure of the extent to which a child born from a parent who makes $X in income will increase his income to $Y (after doing an integral). (See page 10 of the OECD report for the mathematical definition.) Note that a higher elasticity corresponds to a lower probability of increasing your income.

Here's another graph, showing intergenerational earnings elasticity on the vertical axis: enter image description here (Note that the two graphs are based on slightly different definitions of what a person makes, but both still show that that the Nordic countries have a higher probability of increasing your income from $X to $Y than the US.)

  • Those all all measures of absolute mobility. I am interested in how those changes in absolute mobility move a child up/down relative to others within the different quintiles. Do you have that information from those studies? – user1873 Feb 3 '14 at 18:09
  • @user1873 Can't you use absolute mobility to calculate the extent to which a child will move to any given income level? – Keshav Srinivasan Feb 3 '14 at 18:24
  • Good. If you can, you should, since that is what the question is asking. If you do that, I will mark it as accepted. – user1873 Feb 3 '14 at 19:22
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    perhaps it isn't a good measure at all? as this paper notes here, "These measures overcome some of the limitations of traditional measures of intergenerational mobility such as the intergenerational elasticity, which are not well suited for analyzing directional movements or for examining differences in mobility across the income distribution." – user1873 Feb 4 '14 at 5:38
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    It is a good measure for comparing social mobility and economic opportunity between different societies, but it's not a good measure of comparing the mobility and opportunity of rich people and poor people within a society (unless you have a large enough dataset). But that's not necessary in order to calculate the probability to go from one income level to another. – Keshav Srinivasan Feb 4 '14 at 11:47

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