Bioequivalence and Bioavailability Forum

Sample Size II [Power / Sample Size]

posted by BE-proff – 2016-12-28 09:14 (2995 d 03:04 ago) – Posting: # 16892
Views: 10,258

Hi All,

Let's say I want to calculate sample size based on results of a previous study.

I have the following data:
n=20
CV=0.18 (for Cmax and AUC)
GMR1 = 0.97
GMR2=1.19

If to calculate size based on GMR1 I think it's better to use a script:

sampleN.TOST(CV=0.18, theta0=0.95)

+++++++++++ Equivalence test - TOST +++++++++++
            Sample size estimation
-----------------------------------------------
Study design:  2x2 crossover
log-transformed data (multiplicative model)

alpha = 0.05, target power = 0.8
BE margins = 0.8 ... 1.25
True ratio = 0.95,  CV = 0.18

Sample size (total)
 n     power
16   0.820357

if to use GMR = 1.19 we see something terrible:

sampleN.TOST(CV=0.18, theta0=1.19)

+++++++++++ Equivalence test - TOST +++++++++++
            Sample size estimation
-----------------------------------------------
Study design:  2x2 crossover
log-transformed data (multiplicative model)

alpha = 0.05, target power = 0.8
BE margins = 0.8 ... 1.25
True ratio = 1.19,  CV = 0.18

Sample size (total)
 n     power
166   0.803570 - too many people...

What to do in such situations?

Complete thread:

• Sample Size IIBE-proff 2016-12-28 08:14 [Power / Sample Size] 
  • Please see the answer to your previous post mittyri 2016-12-28 09:17
    • Please see the answer to your previous post BE-proff 2016-12-28 10:35
      • Another Master's answer mittyri 2016-12-28 11:38
  • Sample Size II ElMaestro 2016-12-28 10:52
  • Expected power answer d_labes 2016-12-28 13:42
  • Sample Size and regulators DavidManteigas 2016-12-28 18:11
    • Sample Size and sponsors d_labes 2016-12-28 19:24
      • Sample Size and spongulators ElMaestro 2016-12-28 22:22
    • Sample Size and regulators mittyri 2016-12-29 11:44
    • Sample Size and regulators Helmut 2016-12-29 12:39