Z-scores are the content of Table 3. A comment is required regarding the calculation of the mortality rates in the Health Status domain. The rates are adjusted for age because the death rate observed in a population is affected by the demographic composition of that population. The age composition of a population, in particular, is a key factor affecting death rates. For example, the crude death rate, a commonly used death rate derived by dividing the number of deaths in a population by the total population, is very much influenced by age composition and, for that reason, is not of much use in comparing rates between two or more populations.
Standardization is a statistical technique for eliminating the difference in age composition.
Direct standardization is the simplest and most straightforward method for age-adjusting death rates and is the standardization technique used to calculate the mortality rates for the Report Card. For most comparisons, this is the preferred procedure and serves to provide the best basis for determining the relative difference between mortality in two areas. With this technique, a standard population is selected for deriving all the age-adjusted rates in the set of populations or areas to be compared. If the same standard population is employed, all the rates are directly comparable. There are a number of possible choices with respect to the selection of the standard to be used in computing the age-adjusted death rate by the direct method.