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RegisterPower Calculation of 2x2 crossover design (SAS) [Software]
Dear WeirdDude!
Check out:
Section 7.3 - 'Power and sample size for ABE in the 2x2 design' of
B. Jones, M.G. Kenward, "Design and Analysis of Cross-Over Trials", Second edition, Chapman & Hall/CRC 2003.
This section contains the formulas and SAS code for calculating power.
You will have to provide the standard deviation as determined from other sources. Holding the sample size and ratio fixed (@ 24 subjects and a 20% difference as you mentioned), the larger the standard deviation you use, the lower the power.
It should probably be mentioned that with a 20% difference it is very likely your power won't be any where near a level that is acceptable.
❝ Suppose we have 2x2 crossover design with 2 periods, and sample size is given 12 subjects in each seq. (total N=24). How do i calculate power to detect 20% difference between A and B in AUC ? please provide me formula or SAS code!
Check out:
Section 7.3 - 'Power and sample size for ABE in the 2x2 design' of
B. Jones, M.G. Kenward, "Design and Analysis of Cross-Over Trials", Second edition, Chapman & Hall/CRC 2003.
This section contains the formulas and SAS code for calculating power.
❝ what std. deviation should i use ?
You will have to provide the standard deviation as determined from other sources. Holding the sample size and ratio fixed (@ 24 subjects and a 20% difference as you mentioned), the larger the standard deviation you use, the lower the power.
It should probably be mentioned that with a 20% difference it is very likely your power won't be any where near a level that is acceptable.
—
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 1.20 jdetlor 2010-09-28 20:28
- The Abuse of Power Helmut 2010-09-28 22:33
- Power at 1.20 jdetlor 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