The Gallup Potential Net Migration Index estimates what would happen to countries’ populations if everyone in the world who wanted to migrate were able to, and if everyone who wanted to leave were also able to. So the index gives the net national (adult) population growth from unrestricted international migration, or, in other words, national population growth as it would occur when there wouldn’t be immigration restrictions and when all those who desire to migrate permanently to other countries would actually move where they wanted today.
Mathematically, it’s the estimated number of adults who would like to move permanently out of a country if the opportunity arose, subtracted from the estimated number who would like to move into it, as a proportion of the total adult population. A country’s population size affects how high or low its index score is and its ranking, since the score is expressed in terms of the percentage increase or decrease of the pre-immigration population. So a country with a small current population but a relative high number of foreigners wishing to go there, will figure high in the ranking. The absolute numbers of foreigners wishing to go there can, however, be much lower than the number for another country lower in the ranking but with a larger pre-immigration population. That’s why Singapore ranks higher than the U.S., although more people want to migrate to the U.S. If all people were allowed to migrate to the U.S. their impact on the total population number for the U.S. would, however, be smaller.
The index offers an indicator of the relative economic attractiveness of countries, or their relative state of misery.
(source, click to enlarge)
We often focus on what happens to the human rights of migrants once they have migrated: how are they treated when they arrive in a certain country, can they find a job that respects certain minimum labor standards (especially when they are “illegal”), do they end up in poverty, what kind of education to their children get, are they more likely to end up in prison etc. However, it’s obvious that the human rights situation in the country of origin is also relevant, because it’s likely that the desire to migrate – 16% of the world’s population or about 700 million people want to migrate if given the chance - is fueled by rights violations, poverty included.
More maps on migration. And something more on migration and human rights. Some statistics on actual migration are here.

