Bioequivalence and Bioavailability Forum

Dear Compliance,

❝ can any one tell us how to calculate sample size by using power-tost software. we had tried a lot but unable to understand how to use this software.

That's a very broad and unspecific question. Could you please be more elaborate?

Did you read the manual?
Had you had a look at the examples in it?

As a little primer:
Need to estimate the (classical) sample size for a 2x2 crossover. Assumed CV (from previous studies, from pilot study or from literature) is 30% (0.3 as ratio). Assumed distribution is log-normal.
Just type in the R-console:
sampleN.TOST(CV=0.3)
Hit the ENTER key.
That is it, because most of the arguments of the function have reasonable default values. Again, RTFM!

Response after hitting ENTER (printing all the default settings):
+++++++++++ 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
Null (true) ratio = 0.95,  CV = 0.3

Sample size (total)
 n     power
40   0.815845

BTW: I strongly recommend you Helmut's lectures, especially those dealing with sample size estimation. They have at many places hints how it could be done with PowerTOST.

Hope this helps.