Indirect Standardization

Rates (incidence, mortality, etc.) calculated from different study groups or populations are often not directly comparable if the groups differ with regard to the distribution of some characteristic associated with [Page 530]the outcome of interest. Adjustment of rates to facilitate comparison across populations or for the same population across time is called standardization and involves adjusting the crude rates ‘as if’ they were calculated based on the same underlying population. The crude rates are ‘adjusted’ for the characteristic on which the groups differ. For example, if the mortality rates of two different communities are to be compared, but the age distributions of the two communities are sufficiently dissimilar, comparison of the crude rates is inappropriate and will likely yield inaccurate conclusions.

There are two methods of ...