Biostatistics and epidemiology
Crude, specific and standardised rates
Why crude rates mislead when populations differ in age structure, and worked examples of direct standardisation and the standardised mortality ratio (indirect standardisation).
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Crude rate = total events / total population. Easy to calculate and true for that population, but confounded by age (or sex) structure when comparing populations.
- Specific rate = rate within a subgroup (age-specific, sex-specific, cause-specific). The fairest comparison, but there are many of them.
- Standardised rate = one summary figure adjusted for differences in age structure.
- Direct: study population rates applied to a standard population. Gives an age-standardised rate.
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Sources
- Principles on the use of direct age-standardisation in administrative data collections: for measuring the gap between Indigenous and non-Indigenous AustraliansAU/NZAustralian Institute of Health and Welfare, 2011
- Gordis Epidemiology (6th ed.)Elsevier (Celentano and Szklo, 2019), 2019
- Principles of Epidemiology in Public Health Practice (3rd ed.), Lesson 3: Measures of RiskUS Centers for Disease Control and Prevention (2012), 2012
- Australian Demographic Statistics, Mar 2013 (cat. 3101.0), feature article: Standard population for use in age-standardisationAU/NZAustralian Bureau of Statistics, 2013
- Last updated
- 14 November 2026
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