S × F interaction [Design Issues]

posted by Helmut Homepage – Vienna, Austria, 2023-06-07 12:34 (346 d 03:41 ago) – Posting: # 23580
Views: 1,288

Hi Brus,

❝ I don't understand the subject-by-formulation effect, …

You are not alone.

❝ … can it only be studied in full replicated designs?

Yes.

❝ If the subject-by-formulation effect is the change between test and reference difference means from one subject to another, in a 2x2 design it should be possible to study it. Right?

No. In a 2×2×2 crossover we have already aliased effects (are victims of confounding). See this article.
Adding S × F will not work. Didn’t try it yet. Either you get zero degrees of freedom in a fixed effects model or a mixed-effects model will collapse.

❝ And in that case it could also be measured in partial replicate. Right?

Nope.

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