Dr. Jennifer Van Hook

Dr. Jennifer Van Hook

BGSU demographer devising new method for estimating illegal immigrants

At a time of often heated debate about immigration, having a system to regularly provide estimates of the illegal immigrant population has probably never been more important.

A BGSU demographer and two colleagues have been developing a new method for producing those numbers with the support of the U.S. Census Bureau.

Dr. Jennifer Van Hook, sociology, has been awarded $166,000 by the census bureau for her work with Jeffrey Passel of the Pew Hispanic Center and Dr. Frank Bean from the University of California-Irvine. The grant represents a renewal of an award she and her colleagues first received in 2003.

The government says, and Van Hook concurs, that close to 11 million immigrants are now in the country illegally. About 57 percent of them are from Mexico, and the total number is estimated to be growing by 450,000 per year.

Arriving at those figures entails some assumptions, but Van Hook hopes to make them firmer using a method that provides a yearly look at immigration rather than a net picture estimated over the 10 years between censuses.

“The U.S. Census Bureau always needs to have good population estimates, and you need to know how many illegal immigrants there are to refine those estimates,” she says. But since the census doesn’t ask if someone’s an illegal immigrant, getting a count is “tricky,” she adds.

The census does ask for place of birth, duration of residence in the United States and whether the person is a U.S. citizen, “so we have a pretty fair sense of the size of the foreign-born population,” explains Van Hook, who earned a Ph.D. in sociology from the University of Texas in 1996 and has been at BGSU since 1999.

Administrative records—of births, deaths and naturalizations, for example—are used to develop estimates of the legally resident foreign-born population, which in 2000 numbered roughly 23.6 million. At the same time, the 2000 census indicated about 31 million foreign-born people were in the United States, leaving a difference that can be assumed is illegal immigrants—but with assumptions, she points out.

For instance, because foreign-born legal residents leave the country, too, an emigration estimate is built into the legal-resident count. The problem, however, is that the government stopped keeping actual records of “outmigration” of the legally resident foreign-born in the 1950s, so that factor may not be accurately estimated, according to Van Hook.

Described in the May issue of the journal Demography, her method for figuring emigration by that part of the population involves the use of the Current Population Survey (CPS), which is conducted by the census bureau for the U.S. Bureau of Labor Statistics.

The survey covers 60,000 households per month, and about 100,000 in a supplement each March, Van Hook says. Every household is interviewed four consecutive months, and again the following year. If occupants have moved from one year to the next, the new ones are interviewed but the survey notes that they are new residents at the address.

Thus, she continues, information is available about how many people have left surveyed households, whether by death, moving elsewhere in the country or leaving the country. And good estimates of deaths can be found at the National Center for Health Statistics, while internal migration numbers can be determined with data from the CPS, which asks where interviewees lived the previous year. “The leftovers are those who move abroad,” she adds, and in her new grant project, those estimates will be used—along with updated estimates of internal migration devised by Bean—to revise prior estimates of illegal immigrants.

The BGSU demographer and her colleagues are among only a few groups in the nation who are working on “credible estimates” of the illegal population, Van Hook says. Their legacy, she says, will be “a continuous series of estimates” with a consistent methodology, which the census bureau desires so it can produce annual numbers that are as accurate as possible.

Accurate figures are also vital to the government’s interest in the impact of illegal immigration, she notes, saying, for example, that if a “guest worker” program is ever established, it will be helpful to know about how many laborers to expect.

July 3, 2006