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- Standardization is used to reduce the effects of confounding variables like age and gender
- Standardization is necessary to compare mortality or morbidity rates of populations with different age or gender distribution
- Comparing the crude rates of these populations would be misleading due to different age and gender distribution
- Direct and indirect methods of standardization exist
- These methods compare the mortality or morbidity rate of the measured population to the rates of a standard population
- Direct standardization
- Determine the age-specific mortality rates of your measured population
- Apply these mortality rates to the standard population to get the “expected” mortality rate
- Compare the expected mortality rate of the standard population to the measured mortality rate of the measured population
- Indirect standardization
- It is used instead of direct standardization if there is insufficient data or if the population is small
- Yields the standardized mortality ratio (SMR)
- SMR = the number of deaths in the study population / the number of deaths that would be expected in the study population if that population had experienced the death rates of the standard population
- SMR allows comparison of mortality rate with the mortality rate of the standard population or other standardized population
