Understanding Omissions in the Decennial Census

A new report by William P. O’Hare for the Population Reference Bureau (PRB) provides data on omissions in the decennial census. “Understanding Who Was Missed in the 2010 Census” explains that researchers “use two main measures to determine who was missed in the 2010 Decennial Census: omissions and net undercounts. Omissions reflect the number of people who should have been counted in the census but were not, while net undercounts reflect the percent of people who were missed minus the percent who were double counted.”

O’Hare thus contends that, while such data is not widely used or easily available, omissions are a better measure of census accuracy. While both omissions and net undercount “reflect dimensions” of the accuracy of a decennial headcount, “they often tell different stories. Analysis shows a nationwide omissions rate of 5.3 percent compared to a net undercount rate of 0.01 percent.” There were almost 16 million omissions in the 2010 Census.

O’Hare suggested that understanding the demographic characteristics of people missed in the Census can help target 2020 Census outreach efforts. According to the PRB report, “Omissions rates vary among demographic groups in much the same pattern as seen in net undercount rates. Racial and Hispanic minorities have higher omissions rates than non-Hispanic whites. Renters (8.5 percent omissions rate) are more likely than homeowners (3.7 percent) to be omitted in the census. Among the states, omissions rates range from a low of 2.6 percent in Iowa to a high of 8.9 percent in Mississippi. Large cities tend to have higher omissions rates than the rest of the country.”

Read the full report.