Table 2

Minimal effect size that can be detected for the revised sample size given comparison arm risk behaviour prevalence, for a range of ICCs*
Effect size
Risk behaviours Control[7] ICC = 0.01 ICC = 0.04 ICC = 0.07
Alcohol use 41% 11% 13% 15%
Substance abuse 38% 11% 13% 15%
Tobacco use 24% 9% 10% 12%

ICC = Intracluster Correlation Coefficient; Control = comparison arm.

*Calculations assume an 80% power with alpha of 5% for a two-sided test.

Sanci et al.

Sanci et al. BMC Public Health 2012 12:400   doi:10.1186/1471-2458-12-400

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