on the wealth of nation(al)s

Another article that has really caught my eye recently was published through the Center of Global Development by Michael Clemens and Lant Pritchett which attempts to provide an entirely new statistic (I'll try to avoid the temptation to ask if yet another number is what the economics or development professions need right now), what they call 'income per natural'. This is the mean income of persons born in a given country, regardless of where that person now resides. As they put it:

"Most of humanity was born in a “low-income” or “lower middle-income” country. How much money do those people earn each year? No one knows. Armies of statisticians have spent decades carefully estimating how much people in poor countries earn or produce. It is a simple matter to learn the income or output of a person who resides in El Salvador or Albania. But no one has made systematic estimates of the income of a typical Salvadoran or Albanian...[p1]

...[I]f income per resident is used as the measure of Salvadorans’ welfare it leads to untenable conclusions: if a Salvadoran moves from the countryside to San Salvador to get a factory job that raises her income 30%, this will be recorded as a welfare improvement for Salvadorans on average, but a 500% increase in income from a factory job in Texas does not (with, at best, only the portion remitted to residents counted)...[p1]

...42.8 million people live in countries whose income per natural is 50% higher than its income per resident; 235 million people live in a group of countries where the difference is 20% or more, and for 1.1 billion people the difference is 10%...[p1]

...Put differently, for those billion people [for whom the difference between naturals and residents is 10 %] departure from the country is one of the largest national “industries” in terms of its contribution to average material welfare per person of naturals. It is likely that by a reasonable international standard of poverty, two of every five living Mexicans who have escaped poverty did so by leaving Mexico; for Haitians it is four out of five...[p23-4]

This means that departing one’s country of birth is today one of the most important sources of poverty reduction for a large portion of the developing world. If economic development is defined as rising human well being, then a residence-neutral measure of well-being emphasizes that crossing international borders is not an alternative to economic development, it is economic development" [abstract; emphasis added]

These are deliberately provacative (and attention grabbing) words, and I am not at all sure I agree with the polemical level to which they go to emphasise the benefits of migration. I think in order to make a political point about the barriers that put up to the movement of labour they overstep the mark. As much as it is "people, not patches of earth, have well-being", people would most likely attach importance themselves to those patches of earth, and perhaps even more importantly it marginalises production as the single most important global phenomenon. Nevertheless, to focus too much on these conclusions misses the point I think. This new statistic really illuminates more than it obscures, and in that sense I welcome it.