Sample size and power calculations for comparing two independent proportions in a 'negative' trial.

ABSTRACT

Statistical methods for evaluating the adequacy of sample size and power cater mainly to the testing for treatment difference in a 'positive' trial. In biomedical research, the trial can sometimes be postulated as 'negative' to demonstrate that the different treatment groups are statistically equivalent. Herein we describe a computer program to determine the adequacy of sample size and power for comparing two independent proportions in a 'negative' trial. The program is written in MicroSoft QuickBasic Version 4.5, and its executable file is suitable for use as a stand-alone program on a microcomputer.