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RegisterPackage MBESS and Power curiosity [🇷 for BE/BA]
Dear Helmut! Dear all R adepts!
Helmut, as you suggested I have contacted Kem Phillips.
He has confirmed that sigma in case of logscale=TRUE is sqrt(log(1+CV^2)).
He has also confirmed the error if n>344 and will change the code in MBESS accordingly.
With respect to the power curiosity in my post "The Power at limits" above we are still in an ongoing discussion. Kem's first supposition was numerical problems. But considering the results I will present below he is thoughtful.
Because PASS2008 gives the same results I have confronted Jerry Hinze with that curiosity. Here his answer:
"This is surprising to me, but since it occurs in a range that is of little interest, I don't see the need to investigate it further. It could be due to a number of numerical problems that occur when dealing with such a small sample size. However, since as you say, it matches SAS Analyst, I would conjecture that it is probably due to the definition of the equivalence test--that is, the definition probably leads to this result."
For me I had seen the need to investigate it further.
I performed an "in-silico" experiment to obtain an empirical power estimate.
I have simulated data sets for 2x2 cross-over with equal subjects in the two sequences using my beasty number cruncher SAS, performed the TOST and recorded the incidences of stating bioequivalence.
Here my results:
BTW: ElMaestro, can you tell me how Apfelstrudel has found his way to Gent/Belgium
?
As you can see, all results from the different implementations have the same behavior. So Jerry Hinze's presumption seems true that this behavior is inherent to the test definition.
BTW: The empirical power in that region badly converges to a stationary value. One has to use huge number of simulated datasets to obtain a reliable value to some degree. 50.000 is obviously yet to low.
Greetings to all other pettifoggers (Hair splitting needs sharp tools and haven't got anything better to do
).
Helmut, as you suggested I have contacted Kem Phillips.
He has confirmed that sigma in case of logscale=TRUE is sqrt(log(1+CV^2)).
He has also confirmed the error if n>344 and will change the code in MBESS accordingly.
With respect to the power curiosity in my post "The Power at limits" above we are still in an ongoing discussion. Kem's first supposition was numerical problems. But considering the results I will present below he is thoughtful.
Because PASS2008 gives the same results I have confronted Jerry Hinze with that curiosity. Here his answer:
"This is surprising to me, but since it occurs in a range that is of little interest, I don't see the need to investigate it further. It could be due to a number of numerical problems that occur when dealing with such a small sample size. However, since as you say, it matches SAS Analyst, I would conjecture that it is probably due to the definition of the equivalence test--that is, the definition probably leads to this result."
For me I had seen the need to investigate it further.
I performed an "in-silico" experiment to obtain an empirical power estimate.
I have simulated data sets for 2x2 cross-over with equal subjects in the two sequences using my beasty number cruncher SAS, performed the TOST and recorded the incidences of stating bioequivalence.
Here my results:
ratio0=0.95, CV=0.65, BE limits 0.8 ... 1.25
Power SAS EatMyShorts, empirical
Power (R-code with magic DL Apfelstrudel, power
n (MBESS) Owen's Q) (Owen's Q) trapez meffud (50.000 simul.)
----------------------------------------------------------------
4 0.004542 0.004542 0.004542 0.004542 0.00452.
6 0.001620 0.001620 0.001620 0.001620 0.00146.
8 0.000976 0.000976 0.000976 0.000976 0.00086.
10 0.000799 0.000799 0.000799 0.000799 0.00080.
12 0.000797 0.000797 0.000797 0.000797 0.00074.
14 0.000907 0.000907 0.000907 0.000907 0.00084.
16 0.001131 0.001131 0.001131 0.001131 0.00110.
18 0.001501 0.001501 0.001501 0.001501 0.00132.
20 0.002077 0.002077 0.002078 0.002077 0.00230.
22 0.002952 0.002952 0.002952 0.002952 0.00352.
24 0.004253 0.004253 0.004253 0.004253 0.00468.
30 0.012708 0.012708 0.012708 0.012708 0.01216.
40 0.058717 0.058717 0.058717 0.058715 0.05666.
50 0.157587 0.157587 0.157587 0.157587 0.15790.
BTW: ElMaestro, can you tell me how Apfelstrudel has found his way to Gent/Belgium
?As you can see, all results from the different implementations have the same behavior. So Jerry Hinze's presumption seems true that this behavior is inherent to the test definition.
BTW: The empirical power in that region badly converges to a stationary value. One has to use huge number of simulated datasets to obtain a reliable value to some degree. 50.000 is obviously yet to low.
Greetings to all other pettifoggers (Hair splitting needs sharp tools and haven't got anything better to do
).—
Regards,
Detlew
Regards,
Detlew
Complete thread:
- non-central t, power, R: ElMaestro 2009-10-03 19:05 [🇷 for BE/BA]
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- non-central t, power, R: Helmut 2009-10-03 21:45
- non-central t, power, R: ElMaestro 2009-10-04 21:51
- non-central t, power, R: Helmut 2009-10-04 23:58
- non-central t, power, R: ElMaestro 2009-10-04 21:51
- non-central t is not the question d_labes 2009-10-05 12:58
- SAS -> R -> SAS Helmut 2009-10-05 14:53
- Lost in translation d_labes 2009-10-06 14:31
- Lost in translation Helmut 2009-10-06 14:42
- Macacus cynocephalus d_labes 2009-10-06 15:14
- Lost in translation Helmut 2009-10-06 21:46
- Macacus cynocephalus d_labes 2009-10-06 15:14
- Lost in translation Helmut 2009-10-06 14:42
- Lost in translation d_labes 2009-10-06 14:31
- non-central t is not the question ElMaestro 2009-10-05 17:32
- Power of TOST in R d_labes 2009-10-06 16:45
- Power of TOST (R package MBESS) Helmut 2009-10-07 02:18
- Power of TOST (R package MBESS) d_labes 2009-10-07 08:46
- Power of TOST (R package MBESS) Helmut 2009-10-07 12:38
- Power of TOST (R package MBESS) d_labes 2009-10-07 08:46
- The Power at limits d_labes 2009-10-07 11:32
- Power at limits 2 d_labes 2009-10-07 15:15
- package MBESS Helmut 2009-10-07 22:36
- Package MBESS and Power curiosityd_labes 2009-10-15 14:57
- Package MBESS and Power curiosity ElMaestro 2009-10-17 12:26
- Apfelstrudel and EFG 2.01 Helmut 2009-10-17 13:44
- EFG and another power curiosity d_labes 2009-10-20 11:35
- EFG and another power curiosity ElMaestro 2009-11-23 19:03
- EFG and another power curiosity Helmut 2009-11-23 19:17
- EFG and another power curiosity ElMaestro 2009-11-23 19:03
- Package MBESS and Power curiosity ElMaestro 2009-10-17 12:26
- Package MBESS and Power curiosityd_labes 2009-10-15 14:57
- package MBESS Helmut 2009-10-07 22:36
- Power at limits 2 d_labes 2009-10-07 15:15
- Power of TOST (R package MBESS) Helmut 2009-10-07 02:18
- Power of TOST in R d_labes 2009-10-06 16:45
- SAS -> R -> SAS Helmut 2009-10-05 14:53
- non-central t, power, R: yjlee168 2009-10-07 00:08
- R code for power ElMaestro 2009-10-09 11:32
- Belgian beer ? Ohlbe 2009-10-09 11:50
- Another one - R code for power of TROST d_labes 2009-10-09 13:50
- non-central t, power, R: Helmut 2009-10-03 21:45
Ing. Helmut Schütz