ARVO Annual Meeting, May 2012
Sample size and power estimation are essential aspects of clinical trial design. The techniques used to generate these estimates often involve complex statistical calculations and statistical software. Clinical personnel do not necessarily have strong backgrounds in or knowledge about statistics, nor do statisticians always have full clinical backgrounds or knowledge, however it generally requires both clinical and statistical inputs to plan a successful and meaningful trial. The sample size and power tabulations here were developed as a tool to use during protocol development or clinical trial planning. Their use does not require intensive statistical theory and they are easy to use. Using the classic dry eye assessments of corneal staining and ocular discomfort, we have developed tabulations of sample size and power for endpoints with mean difference (MD) ranges from 0.1 to 1 unit and standard deviation (SD) ranges from 0.5 to 1.5 units.