## Full ACK [Power / Sample Size]

Dear David,

» In this case, given your simulations above and the expected probability of approximately 12% of the studies having power greater then 95% having in consideration the initial assumptions, post hoc power means nothing.

Full ACK.

But not only in this case, also in other cases. The concept of post-hoc power is flawed by its own.

» But if you had 100 studies instead and 90% of the had >95% power although the sample size was calculated assuming expected power of 80%, some questions and conclusions might be drawn from those results, don't you think? From my understanding of the initial question, this was the case found. So I think that they should start by reviewing how they define their assumptions for the sample size, namely why they assume GMR=1.10 instead of the "normal" 0.95/1.05.

Again: Full ACK.

» In this case, given your simulations above and the expected probability of approximately 12% of the studies having power greater then 95% having in consideration the initial assumptions, post hoc power means nothing.

Full ACK.

But not only in this case, also in other cases. The concept of post-hoc power is flawed by its own.

» But if you had 100 studies instead and 90% of the had >95% power although the sample size was calculated assuming expected power of 80%, some questions and conclusions might be drawn from those results, don't you think? From my understanding of the initial question, this was the case found. So I think that they should start by reviewing how they define their assumptions for the sample size, namely why they assume GMR=1.10 instead of the "normal" 0.95/1.05.

Again: Full ACK.

—

Regards,

Detlew

Regards,

Detlew

### Complete thread:

- Power is getting high - kms.srinivas, 2017-12-26 07:39 [Power / Sample Size]
- Power is getting high? - d_labes, 2017-12-26 12:08
- Stop estimating post hoc power! - Helmut, 2017-12-26 12:22
- Stop estimating post hoc power! - kms.srinivas, 2017-12-26 13:00
- Stop estimating post hoc power! - ElMaestro, 2017-12-26 14:11
- Simulations - Helmut, 2017-12-26 15:51
- Simulations - BE-proff, 2017-12-27 06:53
- Simulations - ElMaestro, 2017-12-27 07:25
- Simulations - Yura, 2017-12-27 08:23
- Simulations - kms.srinivas, 2017-12-27 09:11
- Simulations - Yura, 2017-12-27 10:07
- α and 1–β - Helmut, 2017-12-27 12:57
- α and 1–β - Yura, 2017-12-27 13:33
- α and 1–β - Helmut, 2017-12-27 14:31
- α and 1–β - Yura, 2017-12-28 06:50
- Educate the IEC and regulators - Helmut, 2017-12-28 11:30

- α and 1–β - Yura, 2017-12-28 06:50

- α and 1–β - Helmut, 2017-12-27 14:31

- α and 1–β - Yura, 2017-12-27 13:33

- α and 1–β - Helmut, 2017-12-27 12:57
- “Forced BE” 101 - Helmut, 2017-12-27 12:23
- “Forced BE” 101 - kms.srinivas, 2017-12-27 12:41
- Would you be so kind answering our questions? - Helmut, 2017-12-27 13:02
- Would you be so kind answering our questions? - kms.srinivas, 2017-12-28 05:53
- Yes, but why? - Helmut, 2017-12-28 11:47
- Yes, but why? - DavidManteigas, 2017-12-28 16:59
- Optimists and pessimists - Helmut, 2017-12-28 17:33
- "normal" GMR setting - d_labes, 2017-12-28 18:57
- Example for discussion - mittyri, 2017-12-28 22:06
- Example for discussion - Helmut, 2017-12-28 22:33

- I prefer to play it safe - Helmut, 2017-12-28 22:10

- Example for discussion - mittyri, 2017-12-28 22:06

- "normal" GMR setting - d_labes, 2017-12-28 18:57
- Full ACK - d_labes, 2017-12-28 17:41
- About GMR 1.10 - kms.srinivas, 2017-12-29 13:20
- Better 0.95 or 0.90 - Helmut, 2017-12-29 16:18

- Optimists and pessimists - Helmut, 2017-12-28 17:33
- Yes, but why? - Yura, 2017-12-29 13:46
- Buffon's needle - Astea, 2018-01-20 23:55
- Buffon's needle - Oleg777, 2018-10-09 22:48
- 0.95 or 1.05 - Helmut, 2018-10-10 13:41

- Buffon's needle - Helmut, 2018-10-10 12:46
- Buffon's needle - Astea, 2018-10-11 23:14
- School maths - Helmut, 2018-10-12 01:10
- School russian - Astea, 2018-10-12 12:41
- Offtop: Umschrift der westlichen Eigennamen auf Russisch - mittyri, 2018-10-12 23:25

- School maths - Helmut, 2018-10-12 01:10

- Buffon's needle - Astea, 2018-10-11 23:14

- Buffon's needle - Oleg777, 2018-10-09 22:48

- Yes, but why? - DavidManteigas, 2017-12-28 16:59

- Yes, but why? - Helmut, 2017-12-28 11:47
- EEU? - mittyri, 2017-12-28 21:52
- EEU? - Yura, 2017-12-29 13:41
- EEU - pharmacokinetic equation??? - mittyri, 2017-12-29 14:11

- EEU? - Beholder, 2018-01-16 15:10

- EEU? - Yura, 2017-12-29 13:41

- Would you be so kind answering our questions? - kms.srinivas, 2017-12-28 05:53

- Would you be so kind answering our questions? - Helmut, 2017-12-27 13:02

- “Forced BE” 101 - kms.srinivas, 2017-12-27 12:41

- Simulations - Yura, 2017-12-27 10:07

- Simulations - kms.srinivas, 2017-12-27 09:11
- Simulations - xtianbadillo, 2018-01-18 22:22

- Simulations - BE-proff, 2017-12-27 06:53

- Stop estimating post hoc power! - kms.srinivas, 2017-12-26 13:00
- Numbers don't lie - ElMaestro, 2017-12-28 20:13