Consequently, standardization method is applied when the differences in the compared sets may affect overall dimensions coefficients.
In order to eliminate the influence of heterogeneity compared formulations the amount of aggregates obtained coefficients of lead to the same standard, it is conventionally assumed that the composition of the compared sets of same. As a standard, you can take part in essence a close third set, the average composition of the two groups being compared, or, more likely, part of one of the groups being compared.
Standardized coefficients indicate what would be the general intensive parameters (fertility, mortality, morbidity, mortality, etc.), if their size were not affected by heterogeneity in the compositions of the groups being compared. Standardized are conditional variables and are used exclusively for the analysis for comparison.
There are three methods of standardization: direct, indirect and reverse (Kerridge).
Consider the application of these three methods of standardization on examples taken from the statistics of cancer. As is well known, are greatly increased with age, death rates from malignant neoplasms. It follows that if, in any city is a relatively high proportion of elderly people, and in the other – to dominate the population of middle-aged, even if the full equality of sanitary living conditions and medical care in both cities is inevitably compared the crude death rate from cancer the first city would be higher than the same ratio in the second city.
In order to neutralize the effect of age on the overall death rate from cancer, you need to apply standardization. Only then can we compare the obtained coefficients and make informed choices about higher or lower death rates from cancer in general compared to the cities.
The direct method of standardization. In our example, it can be applied in the case when we know the age structure of the population and have the information to calculate age-specific death rates from cancer (the number of deaths from cancer in each age group).
Calculation methodology standardized coefficients by the direct method is composed of four successive stages (Table 5.1).