Williams design 3-way [Design Issues]

posted by Helmut Homepage – Vienna, Austria, 2021-06-09 19:48 (1132 d 10:53 ago) – Posting: # 22399
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Hi Brus,

❝ I have a question on this topic that you mentioned a long time ago: […]



Please read the entire thread. What I posted in 2007 is obsolete. See also this article.

❝ According to what you said, 6 sequences had to be done with a 3-way study to get balanced sequences on the two 2x2 tablets. But, with following approach, balanced sequences would also be achieved:


❝ ABC

❝ BAC

❝ CAB

❝ CBA


That’s not balanced for carryover. However, since we cannot correct for unequal carryover anyway (see there), we have to avoid it by design, i.e., sufficiently long washouts between treatment periods.

❝ It's possible? What problems would it have?


What is your idea behind such a design? Actually a simple Latin Square (ABC|BCA|CAB) would do as well. If you want to make European assessors happy, opt for the 6-sequence Williams’ design.

Most important: Evaluate the study by the ‘Two at a Time’ approach.

❝ It is not williams square design, right?


Correct.

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