A relative power table for nested matched case-control studies.
OBJECTIVE
To calculate relative powers for nested case-control studies for different values of both relative risk and numbers of controls per case, given a fixed number of cases available for analysis.


METHODS
Algebraic and numerical methods.


RESULTS
In nested case-control studies, statistical power is a function of relative risk, rarity of exposure, number of case-control sets, and the number of controls per case.


CONCLUSIONS
The dictum that sufficient power will be obtained in a nested case-control study by selecting only four controls per case cannot be sustained. Appropriate numbers need to be calculated for specific studies.
Pang
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Institute of Occupational Health, University of Birmingham, Edgbaston, UK.
D016022:Case-Control Studies; D006801:Humans; D015233:Models, Statistical; D018579:Patient Selection; D012016:Reference Values; D012107:Research Design