Variables Involved in Sample-Size Estimation

Sample-size estimation therefore takes on a special significance in clinical trials. As noted in Section 9.1, this process of estimation does not produce the right answer, so it is not possible to specify precisely what constitutes too few or too many subjects. However, it is imperative to estimate a reasonable sample size based on the best evidence that is available at the time and with full knowledge of the implications of this estimate. 

Several variables need to be considered in the process of sample-size estimation. The values of these variables in any given case can be chosen by the sponsor based on several considerations. Some terms that will be useful for present discussions are  

Action Based on Study Results Research Hypothesis Is True Null Hypothesis Is True 

Fail to reject null Type II error Correct 

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