Conclusion
When the trial’s null hypothesis is no treatment benefit, the best way to ensure the true trial power matches the target power is by setting the assumed benefit to a realistic estimate of the true benefit in the sample size calculation. Attempting to adjust that sample size by taking the minimum important difference into consideration merely leads to an invalid sample size calculation. The minimum important difference should play no role in setting the sample size; however, to provide support for conducting the trial, trialists should report on the minimum important difference and provide the rationale for why the realistic benefit is expected to be (substantially) greater than the minimum important difference.