SEER*Stat Tutorials: Calculating Age-adjusted Rates

An age-adjusted rate is a weighted average of the age-specific (crude) rates, where the weights are the proportions of persons in the corresponding age groups of a standard population. The potential confounding effect of age is reduced when comparing age-adjusted rates computed using the same standard population.

The age-adjusted rate for an age group comprised of the ages x through y is calculated using the following formula:

$a a r a t e_{x - y} = \sum_{i = x}^{y} [(\frac{c o u n t_{i}}{p o p_{i}}) \times 100, 000 \times (\frac{s t d p o p_{i}}{\sum_{j = x}^{y} s t d p o p_{j}})]$

Several sets of standard population data are included in the SEER*Stat software. The SEER Program age-adjusts using the 2000 U.S. standard population based on 20 age groups (0, 1-4, 5-9, 10-14, ..., 80-84, 85-89, 90+). Previously SEER used 19 age groups (0, 1-4, 5-9, 10-14, ..., 80-84, 85+). Refer to the Standard Populations (Millions) for Age-Adjustment website for more information.

In this tutorial, we will demonstrate how to calculate an age-adjusted rate using both the 19 and 20 age groups.

Go to Step 1 to Calculate an Age-Adjusted Rate