What is CDC WONDER?
CDC WONDER (Wide-ranging Online Data for Epidemiologic Research) is a resource that provides a variety of health-related data, which users query and analyze to support public health research and decision-making at national, state, and county levels.
What CDC WONDER Tables are Impacted?
MySidewalk includes data from CDC WONDER’s Natality and Underlying Cause of Death tables. However, only the Underlying Cause of Death tables are affected by the distinction between crude and age-adjusted rates.
Crude and Age-Adjusted Rates
Crude Rates:
Available at the national, state, and county levels.
Crude Rates are expressed as the total number of deaths per 100,000 people in the population without adjusting for the population’s age distribution.
Crude Rate = Count / Population * 100,000
Crude rates are helpful in determining the need for services for a given population, relative to another population, regardless of size.
Age-Adjusted Rates:
Available at the national, state, and county (years 2009-2020) levels.
Age-adjusted death rates are weighted averages of the age-specific death rates, where the weights represent a fixed population by age.
R' = S i ( Psi / Ps ) R i
where Psi is the standard population for age group i and Ps is the total U.S. standard population (all ages combined).
The standard population is an age distribution used to calculate age-adjusted death rates. CDC WONDER uses the 2000 U.S. standard population, based on the proportion of the population in specific age groups in the year 2000.
They are used to compare relative mortality risk among groups and over time.
Age-adjusted rates should be viewed as relative indexes rather than as direct or actual measures of mortality risk.
Why Aren’t Age-Adjusted Rates Available at the County Level?
County-level age-adjusted rates for the CDC WONDER data are currently unavailable for the years 2021 & 2022 and pooled years 2018-2022 due to privacy restrictions imposed by the Census Bureau. These restrictions limit access to detailed population estimates needed for standard age-adjusted calculations. Specifically:
The Census Bureau does not allow sharing population estimates by single-year age groups or “10-year” age groups used in standard age-adjusted calculations.
The restricted age groups include those for <1 year and 1-4 years of age, which are required for calculating the standard age-adjusted rates.
Because of these restrictions, we are unable to provide county-level age-adjusted rates at this time.
How to select Crude or Age-Adjusted rates in mySidewalk Seek or Chart)?
In Seek (top image) and Chart (bottom image), the rate type can be changed by selecting the “Time” drop-down in Seek and “Time Group” in Chart. Crude rates are labeled as CDC Death Rate Years (Crude), while Age Adjusted Rates are labeled as CDC Death Rate Years (Age Adjusted).