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. 2013 Aug 7;19(29):4718–4725. doi: 10.3748/wjg.v19.i29.4718

Table 7.

Sample size requirements for randomized controlled trials based on standardized mean difference

SMD Study design
Parallel groups1 Cross-over
0.2 786 156
0.3 350 71
0.4 198 41
0.5 128 27
0.6 90 19
0.7 66 15
0.8 52 12
1

Total sample size, assuming 1:1 active-to-control group ratio. Assumes two-sided alpha of 0.05 and statistical power of 80%. Attrition estimate not included. SMD: Standardized mean difference.