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With Demography, the Devil Is in the Details—and the Assumptions
May 6, 2009 By Gib ClarkeA micro-economist friend of mine likes to say that macro-economists have correctly predicted nine of the last five recessions. In “The World’s New Numbers,” in the Spring 2009 Wilson Quarterly, Wilson Center Senior Scholar Martin Walker argues that demographers should be so lucky.
Problematic Projections
Demographers base their projections on complex models that incorporate current population numbers, fertility rates, age structures, and other variables. Predicting how many children women and their families will want to have in the future—across different countries and cultures—is not easy. The result is that different demographers get different results. To cover their backs, even the most esteemed organizations offer a range of projected population sizes; the United Nations, for example, says that world population in 2050 will be anywhere from 7.9 to 11 billion people.
As Walker points out, these calculations are often revised. Between 1998 and 2000, for example, the United Nations’ middle projection (or “best guess”) increased by 500 million people. Seemingly miniscule changes in fertility rates often produce big changes in later decades, as Sean Peoples and Liz Leahy explain in the current issue of World Watch magazine.
So Close, and Yet So Far
Why are the projections so far off? Human behavior—particularly the status of women and the availability of family planning—is notoriously hard to predict. Walker points out that the United Nations “rather daringly assumes” that global fertility will drop to 2.02 children per woman by 2050, and to 1.85 further in the future. He doesn’t discuss, however, that these projections are based on an increase in the availability, accessibility, and use of contraceptives in all parts of the world.
Since increased use of contraceptives is highly associated with increases in supply (assuming associated high-quality, culturally sensitive services are provided, including reproductive health education), the burden of reaching global fertility levels of 2.02 and 1.85 is on funders. But when adjusted for inflation, U.S. funding for family planning has declined by almost 40 percent since 1995. We won’t reach the middle UN projection without some significant commitments from the U.S. government and others.
Communicating Probability
With so many (changing) projections and so much nuance, how is demographic information communicated to the public? Poorly, says Walker, with the result that “sensationalist headlines soon become common wisdom.” This “wisdom” includes the belief that Western countries are having fewer babies, aging rapidly, and will soon strain their social safety nets to the breaking point; that mass immigration to Europe is changing the cultural landscape; and that population growth will continue unabated in developing countries for the foreseeable future.
Walker tackles these misconceptions masterfully, pointing to lesser-known or perhaps ignored data. For example, high levels of Arab and Muslim immigration to Europe are unlikely to continue, given that many of the sending countries are experiencing steep declines in birth rates. Meanwhile, birth rates have recently rebounded in several European countries, and social policies such as increasing female participation in the workforce and raising the retirement age may lessen the stress on social safety nets.
Walker does well to point out that 30 countries—mostly in sub-Saharan Africa—continue to grow rapidly, and that they are the least prepared to tackle the challenges associated with rapid growth, given their weak governments, poor economies, and inadequate health and education systems.
Why Bother?
Given the difficulty of making and interpreting projections, why bother with demographic “best guesses” at all? Because the size of a population—and its composition by age, gender, and other variables—impacts many areas, including health care, infrastructure, environmental degradation, and security. So while population projections and economic forecasts may be difficult to parse, basic demographic or financial literacy and the ability to see through sensationalized headlines are essential to understanding both.
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