Instability of Sample Size Calculation
Shein-Chung Chow · Chapman & Hall/CRC biostatistics series · 2011
In clinical trials, a typical approach for clinical evaluation of the safety and efcacy of a test treatment is to rst test for the null hypothesis of no treatment difference in efcacy based on clinical data collected under a valid trial design. The investigator would reject the null hypothesis of no treatment difference and then conclude the alternative hypothesis that there is a difference in favor of the test treatment under investigation. As a result, if there is a sufcient power for correctly detecting a clinically meaningful difference if such a difference truly exists, we claim that the test treatment is efcacious. The test treatment will be reviewed and approved by the regulatory agency if the recommended dose is well tolerated and there appear no safety concerns. In some cases, the regulatory agencies such as the United States FDA will issue a letter of approval pending a commitment for conducting largescale long-term safety surveillance.