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RegisterI prefer to play it safe [Power / Sample Size]
posted by Helmut 
– Vienna, Austria, 2017-12-28 23:10 (2450 d 06:46 ago) – Posting: # 18121
Views: 34,185
Dear Detlew,
Not for me. The former is an assumption whereas the latter fixed by the authority.
Agree.
Agree again.
Communication with the analytical staff & common sense.
The GL tells us that the T- and R-batches should not differ more than 5% in their contents. I’m too lazy to browse through my protocols but IIRC, on the average it was 2–3%. Now add the analytical (in)accuracy and – conservatively assuming that the error may be on opposite sides – you easily end up with a GMR worse than 0.95.
Measuring content is not always trivial. Some MR-products are difficult and most topical products a nightmare. Extracting a lipophilic drug from a cream full of emulsifiers is great fun a mess.
If I have to deal with a simple IR-product, the analytical method is very good, and the difference small I’m fine with 0.95 as well.
In general I prefer conservative assumption(s) over optimistic ones. With the former (if they were false) you may have burned money but have a study which passed. With the latter sometimes you have to perform yet another study. Not economic on the long run.
❝ "Normal" is a question one could debate for hours, probably ending in a flame war 
.
❝ For me 0.95 or 1/0.95 is as "normal" like setting alpha = 0.05.
Not for me. The former is an assumption whereas the latter fixed by the authority.
❝ It's a convention to be used if nothing specific about the GMR is known. Nothing more.
Agree.
❝ And it seemed mostly to work over the years I have observed the use of this setting.
❝ Of course it is not a natural constant.
Agree again.
❝ ❝ ... but IMHO, optimistic even if you measure a content of 100% for both T and R. Given that power is most sensitive to the GMR I question the usefulness of 0.95.
❝
❝ Any other suggestion instead of 0.95 
Communication with the analytical staff & common sense.
The GL tells us that the T- and R-batches should not differ more than 5% in their contents. I’m too lazy to browse through my protocols but IIRC, on the average it was 2–3%. Now add the analytical (in)accuracy and – conservatively assuming that the error may be on opposite sides – you easily end up with a GMR worse than 0.95.
Measuring content is not always trivial. Some MR-products are difficult and most topical products a nightmare. Extracting a lipophilic drug from a cream full of emulsifiers is
If I have to deal with a simple IR-product, the analytical method is very good, and the difference small I’m fine with 0.95 as well.
In general I prefer conservative assumption(s) over optimistic ones. With the former (if they were false) you may have burned money but have a study which passed. With the latter sometimes you have to perform yet another study. Not economic on the long run.
—
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Helmut Schütz
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- Power is getting high kms.srinivas 2017-12-26 07:39 [Power / Sample Size]
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- 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 safeHelmut 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
Ing. Helmut Schütz