WASHINGTON Scientists have devised a formula to allow countries to predict immigration trends, according to a study published on Monday.
The new mathematical model is based on a detailed study of the flow of people into 11 countries including the United States, Britain and Australia from 1960 to 2004, a team led by Joel Cohen of the Rockefeller University in New York said.
The formula looks at factors such as population size and density of the countries people are leaving as well as those they are entering, and the distance between those places.
The mathematical model can be used to predict immigration trends in individual countries and regions, the researchers said, although they did not make such calculations.
"I think that the model we have will permit international institutions and countries to do a much better job of projecting future migrant flows as part of overall population projections," Cohen said in a telephone interview.
With low fertility rates in Europe, the United States and elsewhere, immigration has become an increasingly important factor in population changes worldwide, he said.
Cohen said existing models used by the United Nations and others to predict population flows had been inadequate.
In fact, those models sometimes predict a country will end up with fewer than zero people, he said.
Cohen, who worked with Marta Roig, a U.N. population expert, cited several noteworthy migration flows worldwide.
People from South Asia, including Pakistan and Bangladesh, and from Southeast Asia, including Vietnam and the Philippines, are entering the Gulf states for the oil economies, he said.
Immigrants from Latin America are entering Canada and the United States, while immigrants from the Middle East and Africa are entering Europe, Cohen added.
The formula also was based on data from Belgium, Canada, Denmark, Germany, Italy, the Netherlands, Spain and Sweden.
The findings were reported in the Proceedings of the National Academy of Sciences.
(Editing by Peter Cooney)