Determining how many people live in Seattle, perhaps of a certain age, perhaps from a specific country, is the sort of question that finds its answer in the census, a massive data dump for places across the country.

But just how fresh is that data? After all, the census is updated once a decade, and the U.S. Census Bureau’s smaller but more detailed American Community Survey, annually. There’s also a delay between when data are collected and when they are published. (The release of data for 2016 started gradually in September 2017.)

Enter Facebook, which, with some caveats, can serve as an even more current source of information, especially about migrants. That’s the conclusion of a led by , associate professor of sociology at the 91̽��, published Oct. 11 in Population and Development Review. The study is believed to be the first to demonstrate how present-day migration statistics can be obtained by compiling the same data that advertisers use to target their audience on Facebook, and by combining that source with information from the Census Bureau.

Migration indicates a variety of political and economic trends and is a major driver of population change, Zagheni said. As researchers further explore the increasing number of databases produced for advertisers, Zagheni argues, social scientists could leverage Facebook, LinkedIn and Twitter more often to glean information on geography, mobility, behavior and employment. And while there are some limits to the data – each platform is a self-selected, self-reporting segment of the population – the number of migrants according to Facebook could supplement the official numbers logged by the U.S. Census Bureau, Zagheni said.

“Facebook data are freely available and disaggregated at the level of city or ZIP code in the U.S.,”  Zagheni said. The study focused on Facebook’s Ads Manager service, which allows users, in the interest of placing an ad, to input information on a target audience – information about which the platform then generates data. As an example, researchers identified an audience for a hypothetical ad aimed at Italian expatriates living in Washington state; Facebook reported approximately 3,800 monthly active users in that audience. (That data input process is free; taking it a step further to launch an ad carries a cost.)

Scientists studying migration trends – say, where different groups have located in the United States – could turn to the Facebook Ads Manager tool. But it’s important to recognize biases in the data and some ambiguity in the way migration is measured, Zagheni said. The American Community Survey, in contrast, is the modern incarnation of the old census “long form,” randomly sent to U.S. households annually to collect not only demographic information, but also statistics on housing, jobs and other socioeconomic trends.

In the 91̽��study, Zagheni and his colleagues developed a computer program for extracting data from Facebook Ads Manager about expats from more than 50 countries to every U.S. state, disaggregated by age and sex. The team mined data from a platform of more than 1.8 billion users worldwide, drawing on an innovative statistical model that researchers set up to adjust for the data’s typical shortcoming: Facebook users are not representative of the entire underlying population.

As an illustrative example, Zagheni and colleagues compared the numbers of Mexicans living in California and Texas, by age and sex, with the numbers compiled by the American Community Survey. The researchers did the same with the estimates of immigrants from the Philippines to both states.

The team found that, generally speaking, the numbers of Mexican migrants in California and Texas estimated by Facebook were noticeably lower than the numbers reported by the American Community Survey, particularly among older Mexicans. The American Community Survey, for instance, estimates that Mexican-born men ages 40 to 44 represent more than 20 percent of California’s population of men in that age range; Facebook puts the proportion at closer to 15 percent. Those discrepancies could reflect biases in the data, Zagheni said, such as lower Facebook usage in that demographic group, or differences across age groups in the amount of information posted on Facebook, such as details about users’ hometowns – and thus whether they would be considered an expat.

For immigrants from the Philippines, the differences between Facebook and American Community Survey estimates are narrower, with a potential overestimate of older Filipinos in both states. In Texas, for example, Facebook estimates Filipinos ages 50 to 54 represent 5 percent of the state’s male population in that age range, whereas the American Community Survey estimate is closer to 2.5 percent.

Zagheni and colleagues worked on identifying such biases in the Facebook data, and their similarities among groups or across states. They then developed a model that allows researchers to make adjustments by combining information from Facebook and the American Community Survey.

“Is it better to have a large sample that is biased, or a small sample that is nonbiased? The American Community Survey is a small sample that is more representative of the underlying population; Facebook is a very large sample but not representative,” Zagheni said. “The idea is that in certain contexts, the sample in the American Community Survey is too small to say something significant. In other circumstances, Facebook samples are too biased. With this project we aim at getting the best of both worlds: By calibrating the Facebook data with the American Community Survey, we can correct for the bias and get better estimates.”

The next step, he added, is to test the approach in developing countries, where timely and reliable statistics are important for development.

Zagheni received support from the Washington Research Foundation, the eScience Institute and the Center for Studies in Demography and Ecology at the 91̽��. Co-authors were Ingmar Weber of the Qatar Computing Research Institute in Qatar, and Krishna Gummadi of the Max Planck Institute for Software Systems in Germany.

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For more information, contact Zagheni at 206-616-1173 or emilioz@uw.edu.

A new study looks at just who is doing that caregiving, and who they’re caring for — and some of the findings are surprising.

on June 16, the research is believed to be the first to break down unpaid caregiving in the United States by age and gender of caregivers and those they care for, in their own homes or elsewhere.

The study found that almost one-third of the U.S. population are informal caregivers and collectively provide about 1.2 billion hours of unpaid work weekly, the equivalent of about 30.5 million full-time care aides. But the sandwich generation comprises just 3 percent of the population, much less than researchers anticipated.

The researchers were also surprised to find that elderly people were frequently being cared for by spouses, not their adult children. About 20 percent of caregiving time spent on people 80 years or older comes from people of the same age, they found.

“The extent to which spousal care is prevalent at old ages, 70 and 80 years old, was surprising to us,” said lead author , a 91̽��assistant professor of sociology.

“We expected to see more caregiving by adult children of their parents.”

Older men provided slightly more spousal care than women, Zagheni said, which might be explained by men dying earlier, possibly before they need much care, and women living longer but being in poor health at older ages.

And much less caregiving time was spent on elderly people compared with young children. Across the various age groups, elderly people received caregiving typically no more than 1.5 hours daily, on average, compared with six hours for young children.

The unexpectedly small number of sandwich generation caregivers, Zagheni said, could reflect the fact that while Americans are living longer, people are also having children later, so the two trends might counterbalance each other.

“That could be one reason,” he said. “Or it could be that health overall is improving, so people at older ages don’t need as much help.”

Overall, women continue to shoulder the bulk of the caregiving burden in most situations. They provide 137 minutes of unpaid caregiving a day on average, compared with men’s 110 minutes. Among the sandwich generation, the numbers increase to 181 and 157, respectively.

To develop their analyses, Zagheni and co-author Denys Dukhovnov, a research associate at CUNY Institute for Demographic Research in New York, looked at three years of data from the , which asks respondents how much time they spent the previous day on various activities.

Collected in 2011 through 2013, the data reflects responses from around 36,000 Americans. Zagheni and Dukhovnov broke down responses into five-year age groups for caregivers and recipients, then developed matrices showing who gave and received care in specific age ranges.

While other studies have focused on caregiving within the home or between specific groups, such as middle-aged parents and young children, most have not looked at caregiving by subgroups of people, or a range of caregiving scenarios both inside and outside the home — for example, babysitting a friend’s children or taking a niece or nephew out on weekends.

The study revealed some notable patterns. Childcare occupies a sizable chunk of time for caregivers of various ages, but particularly women in their 30s, and to a lesser degree, in their late 50s and older, underscoring the importance of parenting and grandparenting. And while grandmothers spend considerable time with grandchildren from birth to age 4, grandfathers tend to steer clear of newborns and spend time with grandchildren aged 5 to 14.

Men aged 60 to 79 spend less than one-third of the time caring for children from birth to age 4 than women in the same age group do, but spend slightly more time with children age 5 to 14. While women spend only slightly more time with girls than boys, men spend three times the amount of time with boys as with girls.

The study estimates the value of unpaid care nationwide at $691 billion in 2012, roughly 4.3 percent of the country’s GDP. That figure could rise to $838.8 billion by 2050, the researchers predict, but if caregiving continues at current levels, another 1.3 million more care workers could be needed.

That increased demand, Dukhovnov said, could be partially addressed through more flexible workplace policies and tax breaks or other incentives that would better allow people to provide informal caregiving and continue working.

“Right now, many people must make a choice between staying home to look after parents or children or working,” he said. “If people can work more, that means they’re contributing to the overall economy, and helping to pay for social supports and other care services.”

The U.S., Zagheni said, is currently in a “golden age” of caregiving. Gaps between those who need care and those who are available to provide it are smaller than in the 1950s and ’60s, when high birth rates put a squeeze on caregiver availability, and what we will see in coming years, when the numbers of elderly Americans are expected to increase .

“At least from a demographic perspective, there are enough people in the productive age groups to distribute the work to take care of those who need it, either children or the elderly,” he said. “That’s not going to last.”

But a new study of the worldwide migration of professionals to the U.S. shows a sharp drop-off in its proportional share of those workers – raising the question of whether the nation will remain competitive in attracting top talent in an increasingly globalized economy.

The , which used a novel method of tracking people through data from the social media site LinkedIn, is believed to be the first to monitor global migrations of professionals to the U.S., said co-author , a 91̽�� assistant professor of sociology and fellow of the 91̽��.

“This is the first time a worldwide data set has been used to answer this question,” he said. “That hasn’t been done before.”

The study, which was presented at the recent conference in Barcelona, Spain, found that:

• While 27 percent of migrating professionals among the sample group chose the U.S. as a destination in 2000, in 2012 just 13 percent did.
• The decline was seen across professionals with bachelor’s, master’s and doctoral degrees.
• The biggest drop was among those in the science, technology, engineering and math (STEM) fields, from 37 to 15 percent.
• Asian countries saw the highest increase in professional migrants worldwide, attracting a cumulative 26 percent in 2012, compared with just 10 percent in 2000.
• Australia, Oceania, Africa and Latin America also saw an uptick in their share of the world’s professional migration flows.
• The U.S. attracted 24 percent of graduates from the top 500 universities worldwide in 2000, but just 12 percent in 2012.

“These other countries are attracting not only a higher share of migrants, but also migrants from the top universities in the world,” Zagheni said. “That was surprising.”

The study, which comes at a time when the nation is mired in a divisive fight over immigration reform, counters conventional wisdom that the U.S. is the incontestable top choice for professionals migrating from other countries.

“The U.S. is still the top destination for migrations, but [the study] shows that this is something that should not be taken for granted,” said co-author Bogdan State, who worked on the study as a Stanford University graduate student alongside co-author Mario Rodriguez, a LinkedIn senior data scientist.

The study suggests numerous possible reasons for the proportional migration decline – the U.S.’s complex visa system, greater demand for professionals in other countries, fewer opportunities for immigrants due to the dot-com collapse of the early 2000s and the 2008 recession.

, a 91̽��sociology professor and expert on immigration to the U.S., said the findings underscore the emergence of other nations in sectors once dominated by the United States.

“The United States has to work really hard to stay competitive in this environment,” Hirschman said. “Even if we’re doing everything right, we’re still going to face increasing competition.”

Tracking international migration patterns is key to making fiscal projections and shaping effective policies. But migration data tend to be inconsistent across countries and expensive to gather. And there’s no consensus between nations on what constitutes a migrant.

Zagheni and other researchers realized a few years ago that the borderless and ubiquitous nature of social media made it a virtual goldmine of migration data. In 2012, Zagheni and Ingmar Weber, then a research scientist at Yahoo, the Internet Protocol, or IP, addresses of 43 million Yahoo mail users to calculate migration rates to and from countries worldwide, producing the first-ever curve of U.S. emigration by age and gender.

Earlier this year, Zagheni, State and researchers from the Qatar Computing Research Institute published a that estimated migration patterns among Organization for Economic Cooperation and Development countries by analyzing 500,000 Twitter users. They found that migration rates from Mexico to the U.S. had dropped, while migration increased from European countries hit hard by the economic crisis, such as Greece and Ireland.

Zagheni acknowledges that the LinkedIn research has limitations. For example, since the study did not include citizenship information, researchers couldn’t distinguish between U.S. expatriates returning to the country and in-migration of foreign workers.

More significantly, LinkedIn users aren’t a representative sample of the entire population of highly skilled migrants in the U.S. The researchers addressed that by dividing the data set into 10 groups, one for each new cluster of users annually since 2004, and confirmed that there was a significant downward trend in U.S. migration among all 10 groups.

Respecting the privacy of LinkedIn’s members was a primary concern. LinkedIn researchers used algorithms to generate the dataset used in the study, which did not include any personal information, according to a LinkedIn representative. The company declined to specify how many LinkedIn users were involved in the study.

Zagheni thinks social media data can be valuable to demographers, geographers and economists to help understand long-term migration patterns and develop improved theories. Hirschman lauded the researchers’ work as “a major step forward” in effectively using data from social media.

“This is a very, very creative approach, and I think it’s opening up a whole new world of data analysis that’s going to enrich the field of demography and international migration studies,” he said.

The other co-author is Dirk Helbing, a professor of sociology at ETH Zurich in Switzerland.