Don’t hurry; explore consequences [Study As­sess­ment]

posted by Helmut Homepage – Vienna, Austria, 2014-07-08 12:00 (2705 d 06:58 ago) – Posting: # 13237
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» However, as you mentioned that by considering the obtained T/R ratio, a higher sample size would be required.
» Could you please let me know that what could be in approx sample size if study is repeated?

I strongly suggest not to use values obtained in the study hoping that you get exactly the same ones in a repeated one. They are estimates, not “carved in stone”. Consider reading one of my pre­sen­ta­tions about sample size estimation. You will see that in your case (similar CVs of AUC and Cmax) the ratio is more important. To give you a first idea (using exactly the values for AUC): 78 subjects for 80% power and 108 for 90%.
Get [image] / package PowerTOST and run a sensitivity analysis according to ICH E9:

The method by which the sample size is calculated should be given in the protocol, to­geth­er with the estimates of any quantities used in the calculations (such as variances, mean values, […] difference to be detected). The basis of these estimates should also be given. It is impor­tant to investigate the sensitivity of the sample size estimate to a vari­ety of deviations from these assumptions and this may be facilitated by providing a range of sample sizes appro­pri­ate for a reasonable range of deviations from as­sump­tions.

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