Bioequivalence and Bioavailability Forum • the results of sample size based on PowerTOST

libaiyi
★

China,
2018-07-27 07:34
(2467 d 06:26 ago)

(edited on 2018-07-27 07:47)
Posting: # 19107
Views: 7,529

the results of sample size based on PowerTOST [Software]

Hi,

I have a naive question about the results of sample size based on SampleN.TOST, sampleN.NTIDFDA, sampleN.HVNTID etc.

For example,

sampleN.RSABE(CV=0.3)



++++++++ Reference scaled ABE crit. +++++++++

           Sample size estimation

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

Study design:  2x3x3 (partial replicate) 

log-transformed data (multiplicative model)

1e+05 studies for each step simulated.



alpha  = 0.05, target power = 0.8

CVw(T) = 0.3; CVw(R) = 0.3

True ratio = 0.9

ABE limits / PE constraints = 0.8 ... 1.25

FDA regulatory settings

- CVswitch            = 0.3

- regulatory constant = 0.8925742

- pe constraint applied





Sample size search

 n     power

39   0.75781

42   0.78122

45   0.80344

I want to know if the target power is 0.8, the sample size is 45 for each group or for whole study.

The other question,
when we apply power.TOST, the sample size we need to fill in should be number in each group or whole study.

Third question, :-)

I am confused about the relationship between power and period. Are the power calculation method applied in 2*2, 3*3 and 2*4 designs the same? :-D

For example, if I have the result like this of the study design as T-S-R, could I use the same method to calculate power separately for T-R and S-R? Should I get two power as the result? And, what about parallel design?

[image]

Thanks in advance! :flower:

Helmut
★★★

Vienna, Austria,
2018-07-27 13:24
(2467 d 00:36 ago)

@ libaiyi
Posting: # 19108
Views: 6,634

sample size based on PowerTOST: total number of subjects

Post reply

Hi libaiyi,

answering parts (traveling)…

❝ I have a naive question about the results of sample size based on sampleN.TOST, sampleN.NTIDFDA, sampleN.HVNTID etc.

❝ For example,

❝ sampleN.RSABE(CV=0.3)

❝ …

❝ n power

❝ …

❝ 45 0.80344

❝

❝ I want to know if the target power is 0.8, the sample size is 45 for each group or for whole study.

Type help(sampleN.TOST), etc.
It is always the (total) number of subjects in the study.

❝ when we apply power.TOST, the sample size we need to fill in should be number in each group or whole study.

As above.

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libaiyi ★ China, 2018-07-27 13:49 (2467 d 00:12 ago) @ Helmut Posting: # 19110 Views: 6,580	sample size based on PowerTOST: total number of subjects Post reply
	Hi, Helmut Thanks for answer my question while you are traveling. Enjoy yourself!

ElMaestro
★★★

Denmark,
2018-07-27 21:57
(2466 d 16:04 ago)

(edited on 2018-07-28 11:07)
@ libaiyi
Posting: # 19111
Views: 6,637

the results of sample size based on PowerTOST

Post reply

❝ Hi Libaiyi,

❝

❝ ❝ I am confused about the relationship between power and period. Are the power calculation method applied in 2*2, 3*3 and 2*4 designs the same? :-D For example, if I have the result like this of the study design as T-S-R, could I use the same method to calculate power separately for T-R and S-R? Should I get two power as the result? And, what about parallel design?

❝ ❝

❝ ❝ [image]

That table looks strange. You seem to have a pair for which the CI is not estimable?? And what about alpha 0.1? Would you be after a two-sided CI with 80% coverage (yes I am aware of the ridiculous alpha in the usual SAS code for BE, but is this table derived from one such)?

I have no idea what the intention is, it just looks strange to me, and I am sure that if I got such a table in one of my studies then I would not be answering the question I was really asking.

Edit: screwed up post deleted ;-)

[Ohlbe]

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Pass or fail!
ElMaestro

d_labes
★★★

Berlin, Germany,
2018-07-28 14:43
(2465 d 23:18 ago)

@ ElMaestro
Posting: # 19113
Views: 6,567

Design with not estimable contrast

Post reply

Dear ElMaestro, dear Libaiyi,

❝ That table looks strange...

For me too. Seems Libaiyi has used a design, in which one of the contrasts is not estimable, for what reasons ever. Libaiyi, could you give is some more info about the design and the SAS code used?

❝ And what about alpha 0.1?

That's a peculiarity of the almighty SAS which always calculates a two sided CI, i.e. if you specify alpha=0.05 (the default) it calculates the 95% CI (0.025 to each side) and not the appropriate 90% CI.

—
Regards,

Detlew

libaiyi ★ China, 2018-07-31 06:13 (2463 d 07:48 ago) @ ElMaestro Posting: # 19118 Views: 6,596	the results of sample size based on PowerTOST Post reply
	Hi, ElMaestro Sorry for the SAS result last time, here is the modified result. The design here is a three-period six-sequence William design. I just wondering when the study design is replicated, dose the power calculation method the same as what used in simple 2 by 2 cross over design? Thank you so much!

ElMaestro
★★★

Denmark,
2018-07-31 13:07
(2463 d 00:53 ago)

@ libaiyi
Posting: # 19119
Views: 6,477

the results of sample size based on PowerTOST

Post reply

Hi libaiyi,

❝ The design here is a three-period six-sequence William design. I just wondering when the study design is replicated, dose the power calculation method the same as what used in simple 2 by 2 cross over design? Thank you so much! :lol:

I am still somewhat baffled.
You have different SE's for the three comparisons, possibly suggesting that you are employing an EMA-style BE evaluation?

Anyways, if you are going for a 222BE design, then you can look at your MSE from the ANOVAs (plural, right?), convert them to CVs via CV=sqrt(exp(MSE)-1) and you have a decent variability estimate to plug in for any crossover design with or without scaling.

Your best point estimate is exp(-.2088)~0.81 with upper limit ~0.88, for the T-S pair. The others appear worse. I'd personally think twice, but I am widely known as a backward cowardly chicken.

Note, the opinion above implies logarithms and standard BE thinking.

Edit: Congratulations to your post № 1,500! [Helmut]

—
Pass or fail!
ElMaestro