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posted by Helmut 
– Vienna, Austria, 2010-03-12 12:35 (5950 d 02:04 ago) – Posting: # 4905
Views: 15,872
Dear Dan,
no, you got me wrong.
I was always opposing the 4-way study; reasons:
Almost. I can understand why EMA suggested a 4-way study in the first place. If you perform the comparison between the fasted and fed studies, the confidence intervals will be quite large. The 4-way study would overcome this problem. But since it is only a 'nice to know' term, no more restrictions in the final GL.
But: I would expect that EMA will ask for such a comparison. So plan the two studies as if they are two treatment arms in a parallel design.
no, you got me wrong.
I was always opposing the 4-way study; reasons:
- The variability in fed state may be different to fasted state. Since you have to power the study for the 'weakest' arm, the 4-way study may need more treatments than two 2×2 studies.
- Confounded effects of formulation and food – biased estimates.
- Higher blood loss, drop-out rate like in any other 4-way study.
❝ I totally agree that from a scientific point of view the four-way cross-over study is much more interesting but from a practical (generic company's) point of view you should prefer the other option.
Almost. I can understand why EMA suggested a 4-way study in the first place. If you perform the comparison between the fasted and fed studies, the confidence intervals will be quite large. The 4-way study would overcome this problem. But since it is only a 'nice to know' term, no more restrictions in the final GL.
But: I would expect that EMA will ask for such a comparison. So plan the two studies as if they are two treatment arms in a parallel design.
—
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Helmut Schütz
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- 4-period BE study fed/fasting: statistical issues Amandine 2009-06-04 12:31
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Confounded effects; common variance Helmut 2009-06-04 12:55
- Neglecting period effects? d_labes 2009-06-10 10:10
- Assumptions... Helmut 2009-06-23 14:38
- What if... Ohlbe 2010-03-10 14:27
- What if... Dr_Dan 2010-03-11 15:50
- What if… Helmut 2010-03-11 16:39
- What if… Dr_Dan 2010-03-12 08:49
- Need-to-know / nice-to-knowHelmut 2010-03-12 11:35
- many ANOVA but only one trial boonchai_l 2010-05-24 11:53
- many ANOVA but only one trial GSTATS 2010-06-08 21:52
- many ANOVA but only one trial boonchai_l 2010-05-24 11:53
- Need-to-know / nice-to-knowHelmut 2010-03-12 11:35
- What if… Dr_Dan 2010-03-12 08:49
- What if… Helmut 2010-03-11 16:39
- What if... Dr_Dan 2010-03-11 15:50
- Neglecting period effects? d_labes 2009-06-10 10:10
- Confounded effects; common variance Helmut 2009-06-04 12:55
Ing. Helmut Schütz