Age-adjusted Rates (Directly Age-adjusted)
 

The age-specific rates for each age group in the study population are multiplied by the proportion of people in the same age group in the standard population distribution. The sum of these products is the age-adjusted, or age-standardized rate. The age-adjusted rate can be considered an average of each of the individual age-specific rates, but rather than being a simple average, it is a weighted average with each age-specific rate weighted by the proportion of people in that age group in the U.S. 2000 standard population.

Age-adjusted rates control for age effects, allowing better comparability of rates across areas. Age-adjustment may also be used to control for age effects when comparing across several years of data, as the age distribution of the population changes over time. Only rates adjusted to the same standard population can be compared. Age adjustment is not appropriate if the age-specific death rates in the population of interest do not have a consistent relationship. The age-adjusted rate is hypothetical, and is useful only for comparing populations, either over time, by geographic area, by sex or by racial/ethnic subgroups. For more information, see http://health.utah.gov/opha/IBIShelp/compute_rate2.htm.

Age-adjustment Weights

(last updated September 2005)

The IBIS Query system uses the U.S. 2000 Standard Population Weights for all age-adjusted measures.

U.S. 2000 Standard Population Weights for Age Standardization
  Age Group US 2000 Population Projection, in Thousands Weight
  All Ages 274,634 1.000000
1 Under 1 Year 3,795 0.013818
2 1 - 4 Years 15,192 0.055317
3 5 - 14 Years 39,977 0.145565
4 15 - 24 Years 38,077 0.138646
5 25 - 34 Years 37,233 0.135573
6 35 - 44 Years 44,659 0.162613
7 45 - 54 Years 37,030 0.134834
8 55 - 64 Years 23,961 0.087247
9 65 - 74 Years 18,136 0.066037
10 75 - 84 Years 12,315 0.044842
11 85 Years and Over 4,259 0.015508


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