Standardisation (cont.)

In direct standardisation we take the observed age-specific mortality rates from each population and apply them to a specified standard population Tooltip link with a known age structure. This gives an age-adjusted number of deaths for each study population which can be used for comparisons.

In other words, we compare the two populations by working out how many deaths there would be if each population kept its own observed age-specific mortality rates, but the structure of each population was the same.

The age distribution of an (imaginary) standard population might be something like this:

Age (years) Population
0-29 56,000
30-59 33,000
60+ 11,000
Total 100,000

A standard population can be presented in 1,000s, 10,000s, 100,000s or millions. It does not matter because the numbers are only used to weight the estimates we obtain from the population of interest. In fact, some standard populations are presented as proportions that sum to one.

Interaction Click the "graph" button below to see how the population distribution in Sweden compares with this standard population.

Graph

 

A set of techniques used to remove as much as possible the effects of differences in age or other confounding variables when comparing two or more populations.
A technique by which the specific rates in a study population are averaged, using as weights the distribution of a specific standard population. The directly standardised rate represents what the crude rate would have been in the study population if that population had the same distribution as the standard population with respect to the variable(s) with which the adjustment or standardisation was carried out.
A population in which the age and sex composition is known precisely as result of a census or by arbitrary means. A standard population is used as a comparison group when standardising mortality rates.