EEE and available study power was close to 0.30. In these extreme observations, the ratio of the sample size of the planned study to available study was greater than 4 and given power of the available study was less than 10%. Also, we observed that power calculated by EEE was conservative compared to simulated power in these situations. In general, the majority of the discordance between EEE approximated power and simulation estimated power occurred when the available initial simulated power that was used as input to the EEE formula was less than 10% and sample size for the planned study was more than tripled. In such extreme situations then, investigators should proceed with caution, if at all, with the use of the EEE approximation.
