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J Clin Epidemiol. 2013 Feb;66(2):197-201. doi: 10.1016/j.jclinepi.2012.09.002. Epub 2012 Nov 27.

Sample size calculations for pilot randomized trials: a confidence interval approach.

Author information

1
York Trials Unit, Department of Health Sciences, University of York, Heslington, York YO10 5DD, UK.

Abstract

OBJECTIVES:

To describe a method using confidence intervals (CIs) to estimate the sample size for a pilot randomized trial.

STUDY DESIGN:

Using one-sided CIs and the estimated effect size that would be sought in a large trial, we calculated the sample size needed for pilot trials.

RESULTS:

Using an 80% one-sided CI, we estimated that a pilot trial should have at least 9% of the sample size of the main planned trial.

CONCLUSION:

Using the estimated effect size difference for the main trial and using a one-sided CI, this allows us to calculate a sample size for a pilot trial, which will make its results more useful than at present.

PMID:
23195919
DOI:
10.1016/j.jclinepi.2012.09.002
[Indexed for MEDLINE]

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