Did people in different race groups respond at different rates? How might that affect the quality of the data?
Yes, people in different race groups probably responded at different rates. Although the Census Bureau does not publish race-specific self-response rates, we can see that self-response rates were generally lower in areas with higher shares of people of color. This is not definitive by itself, but alongside previous research on this topic, it strongly suggests that white people were more likely to fill out the census form themselves than people of color.
That said, self-response rates were generally higher overall than in 2010, and we see that increase in most areas of the region, in areas with low and high shares of people of color. Local governments and community organizations invested a lot of resources in encouraging people to respond to the census; these efforts appear to have paid off. Racial differences in response rates almost certainly exist, but they did not grow between 2010 and 2020, which is noteworthy in the face of a pandemic whose effects were felt more severely by people of color.
Any racial differences in response rates have two implications for data quality: (1) some people may have been missed entirely, and (2) data may be less accurate for people who were counted. We provide perspective on those possibilities below.
Were certain groups undercounted?
Yes, some population groups were almost certainly undercounted (that is, a disproportionate share of their members were not included in the 2020 Census results). This is worrisome given the importance of population counts in redistricting, funding allocations, and other government efforts; undercounts of any group dilutes their power.
More broadly, undercounts are one example of “coverage error” – the extent to which the 2020 Census results do not reflect the entire population of the United States. Overcounts are also possible: some people were counted at multiple addresses and appear in the census records more than once. This also distorts the picture of the population drawn by the 2020 Census.
It is difficult to quantify coverage error in our seven-county region, but the Census Bureau’s Post-Enumeration Survey (PES) provides national perspective. This survey essentially conducts a repeat of the census, but for only a sample of the population. Linking the survey participants to the 2020 Census records helps the Census Bureau determine whether someone was not counted or counted more than once.
The first results from the post-enumeration survey were released in March 2022. They show several important findings regarding the net coverage error (including overcounts and undercounts) for different groups:
- Large differences in coverage exist across race groups.
- Hispanic/Latine people and American Indian/Alaskan Natives living on reservations had particularly large undercount rates—5.0% and 5.6% respectively.
- Many stakeholders were concerned about undercounts among the Hispanic/Latine population, in part because of last-minute efforts to add a citizenship question to the 2020 Census. Their worries were not unfounded: the undercount rate for Hispanic/Latine people was nearly 3.5 percentage points higher than in 2010, a much larger increase than seen in any other group.
- Black people were undercounted by 3.3%.
- White, non-Latine people and Asian people were overcounted by 1.6% and 2.6% (respectively).
- Members of other race groups not listed above were undercounted by 4.3%.
- Very young children (under 5) were undercounted by 2.8%—a substantially higher rate than in 2010.
- Adult men were undercounted by 1.3%, and adult women were overcounted by 1.1%
- Renters were undercounted by 1.5%, while homeowners were overcounted by 0.4%.
The PES does not assess the accuracy of the count for noncitizens, which is important given that efforts to add a citizenship question to the 2020 Census may have inhibited candid and complete responses. A recent Urban Institute study estimated that people living in households with noncitizens were undercounted by 3.4%.
The Census Bureau does not edit any 2020 Census counts to account for net coverage error. For more information on coverage error measurement, see the Census Bureau’s website.
In May 2022, the Census Bureau released state-level estimates of coverage error. According to these numbers, Minnesota’s population was overcounted by 3.8%, and it was one of only eight states (primarily in the Northeast) with a statistically meaningful overcount rate. Seven states (primarily in the South) had undercount rates that were statistically meaningful.
Among people who were counted, are there racial differences in data accuracy?
Yes, probably. Because people of color were less likely to provide data themselves than white people, their information needed to be gathered by talking with a neighbor or landlord, or by consulting administrative records. These methods generally yield less accurate data than self-response. For example, a neighbor or landlord might incorrectly identify a person’s age, self-identified race, and/or self-identified Hispanic/Latine origin, particularly if they do not know the person well. Assuming that people of color were more likely than white people to be counted by these less accurate methods, the 2020 Census information is probably less accurate for people of color.