When data points have their own opinions

In this issue, we dive into the science of demography, the study of human populations, through the lens of the U.S. census. An accurate count of the American population was considered so essential by the Founding Fathers that they enshrined the once-a-decade enumeration into the Constitution. But arriving at an accurate count has proven to be a challenge. 

Births, deaths and migration drive population change, and to understand the fabric of a population, demographers often consider age, sex, family and households, as well as education, language, employment, income, wealth, race and ethnicity. 

Demographic data are used to identify economic and social problems and develop solutions to address those problems. The federal government relies on census data to allocate billions in federal aid each year. Industries also use the results to identify trends and develop new markets. Local governments determine where they’ll need new schools or fire stations. Scientists in many fields turn to the data for their own research.

So getting numbers right matters. But the question of people’s race or ethnicity has bedeviled the census from the start, with demographic data often ignored or manipulated to serve political ends, freelance writer Betsy Ladyzhets reports. 

In 1787, the Constitutional Convention battled over how the census data should be used to allocate seats in the House of Representatives; Southern states argued for inclusion of enslaved people, while Northern states argued against that, presumably in an effort to limit the slaveholding states’ power in Congress. South and North compromised on using three-fifths of states’ enslaved populations in apportioning congressional seats and setting federal tax rates. And when Western states entered the Union in the mid-1800s, they argued for the inclusion of Native Americans in the census count to boost their own congressional representation. 

The questions go beyond who gets counted, to how people are categorized. In the 18th and 19th centuries, census enumerators were tasked with knocking on doors and making their own guesses as to a person’s race, a decidedly unscientific process. The rules later changed to allow people to report race or ethnicity themselves, but that hasn’t brought the clarity one might expect, as social sciences writer Sujata Gupta reports. Researchers have found that two people who appear to be racially very similar can define themselves very differently, depending on their nationality and culture. 

And to add even more complexity, the soaring popularity of genetic ancestry tests has prompted a surprising number of people to change their answer to the question: “What is your race?”

This month, people across the United States will start getting invitations to complete the 2020 census. Researchers say they wish it included more nuanced ways to capture both how people see themselves and how they’re seen by the outside world — but that’s a challenge for the next enumeration.

Nancy Shute is editor in chief of Science News Media Group. Previously, she was an editor at NPR and US News & World Report, and a contributor to National Geographic and Scientific American. She is a past president of the National Association of Science Writers.