UMass Donahue Institute

Recently, the Massachusetts Department of Health has been utilizing the UMDI small-area, detailed population estimates as the denominators in the Covid19 case rates they are developing and publishing for Massachusetts municipalities.

The Massachusetts Department of Public Health’s Bureau of Environmental Health publishes disease rates and other health-related incidence rates for specific populations at small-level geographies, including the city, town, and even neighborhood level. To calculate these rates, small-level geography population data (including population by age, sex, race, ethnicity, and geography) are needed on an annual basis.

These population data serve as the denominators when calculating health-related incidence rates. While the Census Bureau enumerates population by age, sex, race, and ethnicity at a very fine level of geography—the census block—it does so only every ten years. In the years following the census, or “post-censual” years, the Census Bureau's Population Estimates Program produces annual estimates of the population down to the town level; however, they break out age, sex, race, and ethnicity only at the county level and higher. Researchers needing detailed population estimates for any sub-county geography must find another source.

To respond to this need, UMass Donahue Institute (UMDI) tested and developed a customized cohort-change-ratio estimates methodology for population estimates. Using this method, UMDI produced annual post-Censual population estimates by age (5-year cohorts ages 0-85+ and single year cohorts ages 0-19), sex, race, and ethnicity at the Census tract and municipal geographic level for years 2010-2019. Small area estimates produced for this project also included associated confidence intervals to inform epidemiologists on estimates reliability in the context of applied work. These estimates are to be utilized as denominators in developing public health-related incidence rates by age, sex, race, and ethnicity cohorts in specific geographies.

Note: This publication was first released in 2016.