lizhao ☆ US, 2016-02-17 20:01 (2961 d 15:27 ago) Posting: # 16003 Views: 8,555 |
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Dear all, For clinical endpoints, I suppose the log-normal distribution doesn't hold, therefore I should use un-transformed data to construct the 90% confidence interval? Then it would be the confidence interval of mean Test/Reference ratio? Am I correct? But then, would the acceptance limits become 80% to 120% instead? If somebody could help me out, it would be greatly appreaciated!! Thanks! |
jag009 ★★★ NJ, 2016-02-17 21:43 (2961 d 13:45 ago) @ lizhao Posting: # 16004 Views: 7,336 |
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Hi, This might help as to why it's 80-120%. http://learnpkpd.com/2011/01/24/where-did-the-80-125-bioequivalence-criteria-come-from/ John |
mittyri ★★ Russia, 2016-02-17 23:34 (2961 d 11:53 ago) @ lizhao Posting: # 16005 Views: 7,370 |
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Hi lizhao, Some example from the ordinary guidance: ❝ For clinical endpoints, I suppose the log-normal distribution doesn't hold, therefore I should use un-transformed data to construct the 90% confidence interval? Then it would be the confidence interval of mean Test/Reference ratio? Am I correct? It could be the difference or the ratio. It is common practice to suppose normal distribution of clinical endpoints. BTW be aware, are you sure that your clinical endpoint is distributed normally? ❝ But then, would the acceptance limits become 80% to 120% instead? Exactly (+/-0.2) — Kind regards, Mittyri |
Helmut ★★★ Vienna, Austria, 2016-02-18 14:38 (2960 d 20:49 ago) @ mittyri Posting: # 16006 Views: 7,263 |
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Dear all, don’t mix up differences with percentages. It’s up to you (maybe supported by a scientific advice) to consider which deviation of the endpoint is clinically relevant. See these threads: #11431, #9534, #1870 and the references given within them. — 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 |
lizhao ☆ US, 2016-02-22 21:20 (2956 d 14:08 ago) @ Helmut Posting: # 16017 Views: 7,036 |
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Dear Helmut and all, Thank you very much for your help! I have done some literature search on Fieller's confidence interval and I am ready to use R to construct the confidence interval. I wonder if you know where I can find some R code/package to compute Fieller's confidence interval? Also, I think the computation depends on parallel or crossover design, as the intrasubject variability would be different? Am I correct? Thanks a lot! |
yjlee168 ★★★ Kaohsiung, Taiwan, 2016-02-23 09:23 (2956 d 02:04 ago) @ lizhao Posting: # 16018 Views: 7,061 |
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Hi lizhao, There is another easy way to calculate Fieller's CI. See this link. Also if you prefer using R/package, see the package mratios . You should be able to find the R codes for Fieller's CI from package mratios . Never use both before. Try it yourself.— All the best, -- Yung-jin Lee bear v2.9.1:- created by Hsin-ya Lee & Yung-jin Lee Kaohsiung, Taiwan https://www.pkpd168.com/bear Download link (updated) -> here |
d_labes ★★★ Berlin, Germany, 2016-02-23 10:08 (2956 d 01:19 ago) @ lizhao Posting: # 16021 Views: 7,003 |
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Dear lizhao, package PowerTOST aka "Swiss army knife for lazy guys dealing with BE studies" has a function CI.RatioF() for calculating the Fieller's confidence interval for the designs "2x2" and "parallel" given estimates of the GMR, CV and CVb(between).The theoretical background can be found in: Hauschke et al. Hauschke D., Steinijans V. and Pigeot I. — Regards, Detlew |