Hi Listers,

I need to calculate the sample necessary for a non-inferiority trial where we are comparing effectiveness of using standard of care vs. a new approach to detect cancer. We know the SoC can detect 80% and we would like to show the new approach is non-inferior using a 10% margin. Participants will undergo both assessments.

IV: binary (yes/no cancer)
DV: binary: SoC vs. new care

Most online information for non-inferiority trials is to compare 2 samples but we only have 1.

I could not find any Stata command to estimate sample size for a non-inferiority trial in one sample. I was advised this could be done using simulations but I am unsure how, I have looked into powersim but I am unsure how to build in the predictor within the cov1 approach (and unsure on how to set it up in general).

powersim , ///
b(0.1) ///
alpha(0.05) ///
pos(1) ///
sample(50(50)400) ///
nreps(500) ///
family(binomial) ///
link(logit) ///
cov1(x1 -0.25 normal 0 1) /// /* how is it defined*/
inside /// /*do i need this*/
dofile(psim_dofile, replace) : /// /*what should this be?*/
glm y i.xi, family(binomial) link(logit)

Any help wold be much appreciated!