Bioequivalence and Bioavailability Forum • Sample size for replicate crossover studies

Imph
★

2023-03-06 15:29
(410 d 07:03 ago)

Posting: # 23487
Views: 1,867

Sample size for replicate crossover studies [Power / Sample Size]

Hi,

For sample size calculation in the case of full replicate design using R software, when specifying the 2x2x4 in the script, do we get the same sample size whether the design is to be : TRTR|RTRT or TRRT|RTTR. And same question for the partially replicated design TRT|RTR vs TRR|RTT.

In the same way for manual computation, can we use the sample size formula presented by CHOW for the TRRT|RTTR design to calculate the sample size for TRTR|RTRT design. And same question, could the sample size formula of TRR|RTT design be used for TRT|RTR design.

Thanks a lot.

dshah ★★ India/United Kingdom, 2023-03-06 16:40 (410 d 05:52 ago) @ Imph Posting: # 23488 Views: 1,590	Sample size for replicate crossover studies Post reply
	HI Imph! The sample size would remain same because it is mainly driven by variability, desired power and ratio. Regards, Divyen

Helmut
★★★

Vienna, Austria,
2023-03-06 17:48
(410 d 04:44 ago)

@ Imph
Posting: # 23489
Views: 1,597

Sample size for replicate crossover studies

Post reply

Hi Imph,

❝ For sample size calculation in the case of full replicate design using R software, when specifying the 2x2x4 in the script, do we get the same sample size whether the design is to be : TRTR|RTRT or TRRT|RTTR.

Yes. See there for the covered designs.

❝ And same question for the partially replicated design TRT|RTR vs TRR|RTT.

These are 3-period full replicate designs. See there for partial replicates.

❝ In the same way for manual computation, can we use the sample size formula presented by CHOW for the TRRT|RTTR design to calculate the sample size for TRTR|RTRT design. And same question, could the sample size formula of TRR|RTT design be used for TRT|RTR design.

Why are you still referring to Chow’s approximations full of typos? At least when you deal with reference-scaling you need simulations anyway. A formula does not – and cannot! – exist.

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Imph ★ 2023-03-07 12:30 (409 d 10:02 ago) @ Helmut Posting: # 23490 Views: 1,566	Sample size for replicate crossover studies Post reply
	Hi, ❝ Why are you still referring to Chow’s approximations full of typos? At least when you deal with reference-scaling you need simulations anyway. A formula does not – and cannot! – exist. I've been asked in my compagny to provide sample size formula for TRTR \| RTRT and TRT \| RTR designs. Thank you all.