## Example for discussion [Power / Sample Size]

» Let me play the devil’s advocate.

Love it.

» Again, a man in Harmani suite as your Boss says it MUST be registered and you have only current product to test. So you are interested to register the drug (to show the bioeqivalence).

» What would be your recommendation for sample size? How would you estimate it?

“

**Must**be registered” is a bit thick! Try…

`library(PowerTOST)`

expsampleN.TOST(CV=0.2, theta0=1.15, prior.type="both",

prior.parm=list(m=20, design="2x2"),

details=FALSE)

^{7}subjects would be required. Since re-formulation seems not to be an option (what I strongly would recommend; see below why) you will be fired.

Seriously: First I would check a CI of the CV observed in the pilot. I would use an α of 0.2.

`signif(100*CVCL(CV=0.2, df=20-2, side="2-sided", alpha=0.2), 4)`

lower CL upper CL

16.59 25.91

`sampleN.TOST(CV=CV.upper, theta0=1.15, targetpower=0.9)`

+++++++++++ Equivalence test - TOST +++++++++++

Sample size estimation

-----------------------------------------------

Study design: 2x2 crossover

log-transformed data (multiplicative model)

alpha = 0.05, target power = 0.9

BE margins = 0.8 ... 1.25

True ratio = 1.15, CV = 0.2794244

Sample size (total)

n power

188 0.901956

`pa.ABE(CV=signif(CV.upper, 4), theta0=1.15,`

targetpower=0.9, minpower=0.80)

pa.ABE(CV=signif(CV.upper, 4), theta0=1.15,

targetpower=0.9, minpower=0.85)

*such*a large expected deviation will be welcomed. I know of only one case where an innovator had to change one of the excipients upon the FDA’s demand. A couple of pilots with candidate formulations performed – wasn’t possible to come up with anything better than 0.85. OK, was a blockbuster and at least they tried hard.

Cheers,

Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. ☼

Science Quotes

### Complete thread:

- Power is getting high kms.srinivas 2017-12-26 07:39
- Power is getting high? d_labes 2017-12-26 12:08
- Stop estimating post hoc power! Helmut 2017-12-26 12:22
- Stop estimating post hoc power! kms.srinivas 2017-12-26 13:00
- Stop estimating post hoc power! ElMaestro 2017-12-26 14:11
- Simulations Helmut 2017-12-26 15:51
- Simulations BE-proff 2017-12-27 06:53
- Simulations ElMaestro 2017-12-27 07:25
- Simulations Yura 2017-12-27 08:23
- Simulations kms.srinivas 2017-12-27 09:11
- Simulations Yura 2017-12-27 10:07
- α and 1–β Helmut 2017-12-27 12:57
- α and 1–β Yura 2017-12-27 13:33
- α and 1–β Helmut 2017-12-27 14:31
- α and 1–β Yura 2017-12-28 06:50
- Educate the IEC and regulators Helmut 2017-12-28 11:30

- α and 1–β Yura 2017-12-28 06:50

- α and 1–β Helmut 2017-12-27 14:31

- α and 1–β Yura 2017-12-27 13:33

- α and 1–β Helmut 2017-12-27 12:57
- “Forced BE” 101 Helmut 2017-12-27 12:23
- “Forced BE” 101 kms.srinivas 2017-12-27 12:41
- Would you be so kind answering our questions? Helmut 2017-12-27 13:02
- Would you be so kind answering our questions? kms.srinivas 2017-12-28 05:53
- Yes, but why? Helmut 2017-12-28 11:47
- Yes, but why? DavidManteigas 2017-12-28 16:59
- Optimists and pessimists Helmut 2017-12-28 17:33
- "normal" GMR setting d_labes 2017-12-28 18:57
- Example for discussion mittyri 2017-12-28 22:06
- Example for discussion Helmut 2017-12-28 22:33

- I prefer to play it safe Helmut 2017-12-28 22:10

- Example for discussion mittyri 2017-12-28 22:06

- "normal" GMR setting d_labes 2017-12-28 18:57
- Full ACK d_labes 2017-12-28 17:41
- About GMR 1.10 kms.srinivas 2017-12-29 13:20
- Better 0.95 or 0.90 Helmut 2017-12-29 16:18

- Optimists and pessimists Helmut 2017-12-28 17:33
- Yes, but why? Yura 2017-12-29 13:46
- Buffon's needle Astea 2018-01-20 23:55
- Buffon's needle Oleg777 2018-10-09 22:48
- 0.95 or 1.05 Helmut 2018-10-10 13:41

- Buffon's needle Helmut 2018-10-10 12:46
- Buffon's needle Astea 2018-10-11 23:14
- School maths Helmut 2018-10-12 01:10
- School russian Astea 2018-10-12 12:41
- Offtop: Umschrift der westlichen Eigennamen auf Russisch mittyri 2018-10-12 23:25

- School maths Helmut 2018-10-12 01:10

- Buffon's needle Astea 2018-10-11 23:14

- Buffon's needle Oleg777 2018-10-09 22:48

- Yes, but why? DavidManteigas 2017-12-28 16:59

- Yes, but why? Helmut 2017-12-28 11:47
- EEU? mittyri 2017-12-28 21:52
- EEU? Yura 2017-12-29 13:41
- EEU - pharmacokinetic equation??? mittyri 2017-12-29 14:11

- EEU? Beholder 2018-01-16 15:10

- EEU? Yura 2017-12-29 13:41

- Would you be so kind answering our questions? kms.srinivas 2017-12-28 05:53

- Would you be so kind answering our questions? Helmut 2017-12-27 13:02

- “Forced BE” 101 kms.srinivas 2017-12-27 12:41

- Simulations Yura 2017-12-27 10:07

- Simulations kms.srinivas 2017-12-27 09:11
- Simulations xtianbadillo 2018-01-18 22:22

- Simulations BE-proff 2017-12-27 06:53

- Stop estimating post hoc power! kms.srinivas 2017-12-26 13:00
- Numbers don't lie ElMaestro 2017-12-28 20:13