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Sample Size Calculations with Dropouts in Clinical Trials
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 Title & Authors
Sample Size Calculations with Dropouts in Clinical Trials
Lee, Ki-Hoon;
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The sample size in a clinical trial is determined by the hypothesis, the variance of observations, the effect size, the power and the significance level. Dropouts in clinical trials are inevitable, so we need to consider dropouts on the determination of sample size. It is common that some proportion corresponding to the expected dropout rate would be added to the sample size calculated from a mathematical equation. This paper proposes new equations for calculating sample size dealing with dropouts. Since we observe data longitudinally in most clinical trials, we can use a last observation to impute for missing one in the intention to treat (ITT) trials, and this technique is called last observation carried forward(LOCF). But LOCF might make deviations on the assumed variance and effect size, so that we could not guarantee the power of test with the sample size obtained from the existing equation. This study suggests the formulas for sample size involving information about dropouts and shows the properties of the proposed method in testing equality of means.
Clinical trials;sample size;LOCF;ITT;
 Cited by
침구 임상시험에서의 중도탈락 관련요인,김애란;이무식;홍지영;

대한한의학회지, 2011. vol.32. 4, pp.128-138
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