Achievwin ★ US, 20240503 15:43 (19 d 03:17 ago) Posting: # 23977 Views: 743 

Recently I was asked to give Probability of success for a proposed BE study, My thinking is Target study power (usually 80%) is POS with additional correction factor due to the variability during study conduct applied to this target power, is my understanding correct? Challenge is that do you substract or a multiply the variability factor? e.g. POS = Target Power (90)  30 (CV)= 60 0r 90X(10.30)=63% Achievwin 
Helmut ★★★ Vienna, Austria, 20240503 16:15 (19 d 02:45 ago) @ Achievwin Posting: # 23979 Views: 657 

Hi Achievwin, ❝ Recently I was asked to give Probability of success for a proposed BE study, My thinking is Target study power (usually 80%) is POS with additional correction factor due to the variability during study conduct applied to this target power, is my understanding correct?
— Diftor heh smusma 🖖🏼 Довге життя Україна! _{} Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 
Achievwin ★ US, 20240506 16:49 (16 d 02:10 ago) @ Helmut Posting: # 23985 Views: 568 

❝ Not sure whether I understand you correctly. POS is a Bayesian concept, where you need some prior information. I am sorry I am equally confused in this example where do we find POS? what all I see is Sample size and anticipated power with certain N. How come we have three different N with same assumptions? ❝ As usual, the T/Rratio is the killer.  Thanks for reiterating my thought all along many of my colleagues are having issue in understanding T/R is main culprit than ISCV in Sample size estimates. Please edcuate me on how to connect Power with POS? Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post #5! [Helmut] 
d_labes ★★★ Berlin, Germany, 20240506 17:16 (16 d 01:43 ago) @ Achievwin Posting: # 23986 Views: 564 

Hi Achievwin, ❝ I am sorry I am equally confused in this example where do we find POS? what all I see is Sample size and anticipated power with certain N. What you see is sample size and expected power! Expected power is synonym with Probability of success. Sometimes also called assurance. If you have need consult the file 'Expected_Power_for_TOST.pdf' in the docs folder ( c:\Program Files\R\library\PowerTOST\doc\ for my installation) of the package PowerTOST . Its a little bit theoretic and mainly mathematical but describes in a comprehensive manner what expected power is and how it will be calculated.— Regards, Detlew 
Achievwin ★ US, 20240506 17:31 (16 d 01:28 ago) @ d_labes Posting: # 23988 Views: 554 

Thank you for the take home message ❝ Expected power is synonym with Probability of success. Sometimes also called assurance. 
Helmut ★★★ Vienna, Austria, 20240506 17:31 (16 d 01:29 ago) @ Achievwin Posting: # 23987 Views: 554 

Hi Achievwin, ❝ How come we have three different N with same assumptions?
m ). The smaller, the larger the sample size of the next. Therefore, small pilot studies are not a good idea. It may sound stupid, but the best for sample size estimation is a failed pivotal study… — Diftor heh smusma 🖖🏼 Довге життя Україна! _{} Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 
Achievwin ★ US, 20240506 17:51 (16 d 01:08 ago) @ Helmut Posting: # 23989 Views: 546 

❝ ❝ How come we have three different N with assumptions? ❝ … three assumptions, ❝ 1. Uncertain CV → n = 28 ❝ 2. Uncertain T/Rratio → n = 44 ❝ 3. Uncertain CV and uncertain T/Rratio → n = 48 Thank you Helmut.... now even I can understand...... 