Intercensal and Postcensal Estimation of Population Size for Small Geographic Areas in the United States

Abstract

Introduction: Population estimation techniques are often used to provide updated data for the current year. However, estimates for a finer geographic scale, such as census tract in the United States, are typically not available. Yet there are growing demands from public health practitioners for such data, because it is more useful than larger scales for local policy making, program planning and evaluation. Objectives: To estimate the population size at the block level by subgroups (age, sex, and race/ethnicity) so that the data can be aggregated up to any target small geographic area. Methods: We estimated the population size by subgroups at the block level using an intercensal approach for years between 2000 and 2010 and a postcensal approach for the years following the 2010 decennial census (2011-2017). Then we aggregated the data to the county level (intercensal approach) and incorporated place level (postcensal approach) and compared our estimates to corresponding US Census Bureau (the Census) estimates. Results: Overall, our intercensal estimates were close to the Census’ population estimates at the county level for the years 2000-2010; yet there were substantive errors in counties where population size experienced sudden changes. Our postcensal estimates were also close to the Census’ population estimates at the incorporated place level for years close to the 2010 decennial census. Conclusions: Both approaches presented here were able to produce population estimates for small areas with acceptable errors. The advantages and disadvantages of their application in public health practice are considered.

Keywords

• Interpolation; extrapolation; population estimation; decennial census