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Jérôme Martin ☆ France, 2013-08-27 20:28 (4334 d 21:58 ago) Posting: # 11363 Views: 4,651 |
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Hello everybody, I have theoretical questions about computing BE and making the link with statistical model. Considering the statistical linear model for cross-over design : Xijlk = µ + Tl + Pk + SEj + SUi|SEj + eijklWith: Xijlk: ln-transformed responseI have two questions: 1/ did I write this statistical model correctly for a 2x2x2 cross-over design? I assume T + P + SE + SU|SE are the CVinter and eijkl the CVintra. I am right? Why in the bebac presentations there is multiplicative model roughly the same with “*” instead of “+” and withoud the nested part “SUi|SEj” I have found in other references? Any relevant links?2/ in PowerTOST (nice package!), I enter the T/R ratio when I use the power.TOST() function (I suppose that’s T in my model) and CVintra that corresponds to eijkl, did it suppose that there is no effect of P (period), SE (sequence) and SU|SE (subject nested in sequence)? Thanks to the people who will try to respond to these deep questions for me! Jérôme |
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ElMaestro ★★★ Denmark, 2013-08-27 21:52 (4334 d 20:34 ago) @ Jérôme Martin Posting: # 11364 Views: 3,625 |
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Hi J M, ❝ I have theoretical questions about computing BE and making the link with statistical model. Considering the statistical linear model for cross-over design : ❝ ❝ ❝ With: ❝ ❝ µ: overall mean ❝ Tl: fixed formulation effect ❝ Pk: fixed period effect ❝ SEj: fixed sequence effect ❝ SUi|SEj: random effect of the ith subject in the jth sequence (nested) ❝ eijkl: independent random effects ❝ ❝ I have two questions: ❝ 1/ did I write this statistical model correctly for a 2x2x2 cross-over design? I assume For EU you will need to treat the subject effect as fixed. Depending on your coding your may or may not want/need to speak of the nesting. "ijlk".... do you use another version of the alphabet in France?  ❝ Why in the bebac presentations there is multiplicative model roughly the same with “*” instead of “+” and withoud the nested part “SUi|SEj” I have found in other references? Any relevant links? Yeah, even oracles make mistakes. "Xijk: ln-transformed response of j-th subject" he meant un-transformed as long as we have * signs between factors. ❝ 2/ in PowerTOST (nice package!), I enter the T/R ratio when I use the power.TOST() function (I suppose that’s T in my model) and CVintra that corresponds to eijkl, did it suppose that there is no effect of P (period), SE (sequence) and SU|SE (subject nested in sequence)? This is the wrong question. Sequence, Period, Subjects effects do not influence our decision about BE. Period and Sequence effects are nuissance effects. Subjects differ generally - in most studies you will see a P-value that is low. — Pass or fail! ElMaestro |
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Helmut ★★★   Vienna, Austria, 2013-08-28 15:56 (4334 d 02:30 ago) @ ElMaestro Posting: # 11369 Views: 3,608 |
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Hi ElMaestro & Jérôme, ❝ ❝ Why in the bebac presentations there is multiplicative model roughly the same with “*” instead of “+” and withoud the nested part “SUi|SEj” I have found in other references? Any relevant links? ❝ ❝ Yeah, even oracles make mistakes. ❝ "Xijk: ln-transformed response of j-th subject" he meant un-transformed as long as we have * signs between factors. Oh no! Of course it should read “untransformed”. THX for finding this error! — Dif-tor heh smusma 🖖🏼 Довге життя Україна! ![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png) Helmut Schütz ![[image]](https://static.bebac.at/img/CC by.png) The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes |
Ing. Helmut Schütz