overpowering [General Statistics]
Hi BE-proff
Generally we plan studies for 80–90% power π (where the producer’s risk of failing to demonstrate BE of a formulation which is BE: Type II Error, β = 1 – π). If you submit a protocol to the IEC which >90%, they might not accept it. Hence, “overpowered”. Sometimes rich sponsor know that the CV will be lower and/or the T/R is closer to 100% than what they present in the sample size estimation. Protocol approved, study done, low risk of failure. They call it “to be on the safe side”. I call it playing dice with the health of subjects.
Sometimes the minimum sample size given in guidelines will lead to high power anyway. Example – T/R 0.95, 2×2 crossover, AR 80–125%; CVs which will lead to >90% power:
Imagine: n 134, T/R 0.97, CV 15%. The 90% CI will be 94.12–99.97%. 100% not included, significant treatment effect (p 0.0485), bingo. Is it relevant? Not at all. You can be >99.9999999999999% sure that the true T/R-ratio is not below 80%…
Negative producer’s risk‽
❝ overpowered study...what do you mean?
Generally we plan studies for 80–90% power π (where the producer’s risk of failing to demonstrate BE of a formulation which is BE: Type II Error, β = 1 – π). If you submit a protocol to the IEC which >90%, they might not accept it. Hence, “overpowered”. Sometimes rich sponsor know that the CV will be lower and/or the T/R is closer to 100% than what they present in the sample size estimation. Protocol approved, study done, low risk of failure. They call it “to be on the safe side”. I call it playing dice with the health of subjects.
Sometimes the minimum sample size given in guidelines will lead to high power anyway. Example – T/R 0.95, 2×2 crossover, AR 80–125%; CVs which will lead to >90% power:
n CV%
most regulations, Russian “Red Book”
12 ≤13.3
18 ≤16.6
2008 Russian GL
20 ≤17.9
South Africa MR
24 ≤19.8
Brazil, Saudia Arabia (unless justified otherwise)
Imagine: n 134, T/R 0.97, CV 15%. The 90% CI will be 94.12–99.97%. 100% not included, significant treatment effect (p 0.0485), bingo. Is it relevant? Not at all. You can be >99.9999999999999% sure that the true T/R-ratio is not below 80%…
❝ Power over 100%?
Negative producer’s risk‽
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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
Complete thread:
- Factors influence in Anova BE-proff 2015-11-05 18:31 [General Statistics]
- Factors influence in Anova Helmut 2015-11-05 19:33
- Factors influence in Anova felipeberlinski 2015-11-05 19:56
- Factors influence in Anova Helmut 2015-11-05 20:27
- What else? ElMaestro 2015-11-05 21:28
- Factors influence in Anova BE-proff 2015-11-05 21:27
- overpoweringHelmut 2015-11-06 04:03
- Factors influence in Anova felipeberlinski 2015-11-05 19:56
- Factors influence in Anova Helmut 2015-11-05 19:33