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RegisterPower at 1.20 [Software]
Dear HS!
Don't get me wrong — I am not advocating that planning a study with 20% is by any means acceptable. But, what I am saying is that technically it is possible to demonstrate BE with a ratio of 120%. If you were to plot the observed power vs the p-value, we would only need a power of approximately 34%[1] to have the 90% BE confidence interval to fall within the BE limits, which puts us (according to the table) at a CV of about 11%.
[1] See Figure 1 in The Abuse of Power: The Pervasive Fallacy of Power Calculations for Data Analysis
❝ Yes, I’ve heard the term ‘forced BE’ also. If WeirdDude really talked about a ratio of 1.20 – well, let’s see what power we would get (24 subjects, usual settings, 
):
❝ CV% power
❝ 5.5 0.8017
❝ 10 0.3932
❝ 20 0.1704
❝ 30 0.1180
❝ Unless one has to deal with the ‘wonder-drug’ (CV 5.5 %), 24 subjects at a ratio of 1.20 are futile.
Don't get me wrong — I am not advocating that planning a study with 20% is by any means acceptable. But, what I am saying is that technically it is possible to demonstrate BE with a ratio of 120%. If you were to plot the observed power vs the p-value, we would only need a power of approximately 34%[1] to have the 90% BE confidence interval to fall within the BE limits, which puts us (according to the table) at a CV of about 11%.
[1] See Figure 1 in The Abuse of Power: The Pervasive Fallacy of Power Calculations for Data Analysis
—
J. Detlor
J. Detlor
Complete thread:
- Power Calculation of 2x2 crossover design (SAS) weirddude100 2010-09-21 18:13
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- Power Calculation of 2x2 crossover design (SAS) jdetlor 2010-09-21 19:14
- Power at the limits of the acceptance range Helmut 2010-09-28 17:50
- Power at the limits of the acceptance range jdetlor 2010-09-28 18:37
- Power at 1.20 Helmut 2010-09-28 18:57
- Power at 1.20jdetlor 2010-09-28 20:28
- The Abuse of Power Helmut 2010-09-28 22:33
- Power at 1.20jdetlor 2010-09-28 20:28
- Power at 1.20 Helmut 2010-09-28 18:57
- Power at the limits of the acceptance range jdetlor 2010-09-28 18:37
- Power at the limits of the acceptance range Helmut 2010-09-28 17:50
- Power Calculation of 2x2 crossover design (SAS) d_labes 2010-09-27 08:51
- Power Calculation of 2x2 crossover design (SAS) jdetlor 2010-09-21 19:14
Ing. Helmut Schütz