EPI5.2: STANDARDIZATION: CRUDE RATES VERSUS STANDARDISED MEASURES

OBJECTIVE

At the end of this session you should understand the difference between crude and standardised measures. Measures could be of occurrence or effect.

CRUDE RATES VERSUS STANDARDISED MEASURES:

Thus far we have only been talking about crude or unadjusted effect measures.

The crude rate is just the total number of events in the population of interest divided by the total population. It constitutes the actual experience of the population in terms of numbers of events per population.

Typically, mortality rates vary considerably by age in any population. Populations also differ with respect to their age composition. In this way age-composition of a population introduces distortion into a crude measure of mortality.

In order to compare different populations with different age structures it is necessary to remove this distortion by adjusting the crude rates so that they are comparable. We adjust the crude rate by means of standardisation. The next page will show an example of this.




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General Introduction to Occupational Health: Occupational Hygiene, Epidemiology & Biostatistics by Prof Jonny Myers is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License
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