In this report, we define “young children” as children age 0 to 4. After the 2010 Census, Demographic Analysis estimated a net undercount of almost 1 million young children, about 4.6 percent (Hogan et al. 2013). O’Hare (2015) shows that the net undercount rates for young children increased from 1.4 percent in 1980 to 4.6 percent in 2010, while the net undercount rate for the adult population (age 18+) went from an undercount of 1.4 percent in 1980 to an overcount of 0.7 percent in 2010. The rapid rise in the undercount of young children underscores the importance of examining this coverage problem in greater detail.

In 2014, the Census Bureau released a task force report summarizing this issue and recommending research to better understand the possible causes for this undercount (U.S. Census Bureau 2014). An interdivisional team is currently working on several projects to review existing data sources that might provide insights into the high undercount of young children in the 2010 Census. This report analyzes responses to the 2010 Census coverage questions to identify households that might have had some confusion about whether or not to include a young child on their 2010 Census forms.