Bebac user ☆ Egypt, 2022-03-23 10:38 (956 d 20:35 ago) Posting: # 22860 Views: 4,219 |
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Partially replicated study, I use this code for sample size estimation sampleN.scABEL(CV=0.3532) But, I know that I can't use more than 40 volunteers in any BE study In these cases, what should I do ? |
dshah ★★ India, 2022-03-23 12:30 (956 d 18:43 ago) @ Bebac user Posting: # 22861 Views: 3,473 |
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Dear Bebac user! As your ISCV is high, you are opting for partial/fully replicate design. But why the 90% BE range is still 80.00-125.00% where you know that you can apply the HVD concept to widen the boundary? Regards, Divyen Shah |
Helmut ★★★ Vienna, Austria, 2022-03-23 13:43 (956 d 17:30 ago) @ dshah Posting: # 22863 Views: 3,444 |
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Hi Divyen, ❝ But why the 90% BE range is still 80.00-125.00% where you know that you can apply the HVD concept to widen the boundary? Seemingly the output of the function sampleN.scABEL() is not clear enough. It gives:
See this article for the decision scheme. In coding the function sampleN.scABEL.ad() I tried to be more specific (see also my post below) and it gives for \(\small{CV_\textrm{wT}=CV_\textrm{wR}=0.3532}\):
Note that the sample size tables of the ‘The Two Lászlós’* don’t reach below \(\small{CV_\textrm{wR}=30\%}\). They state: »In view of the consequences of the mixed approach, it could be judicious to consider larger numbers of subjects at variations fairly close to 30%.« You could assess at which \(\small{CV_\textrm{wR}}\) (on the average) we will switch in the simulations.
— 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 |
d_labes ★★★ Berlin, Germany, 2022-03-23 17:33 (956 d 13:40 ago) @ Helmut Posting: # 22865 Views: 3,443 |
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Dear Helmut, ❝ In coding the function
❝ Switching CVwR : 0.3 ❝ Regulatory constant: 0.76 ❝ Expanded limits : 0.7706 ... 1.2977 ❝ Upper scaling cap : CVwR > 0.5 ❝ PE constraints : 0.8000 ... 1.2500 ...The Expanded limits are only valid if the CV's are exactly the assumed ones. They don't play any role during the simulations because the expansion applied depends on the CVwR of actual study, gradually different from study to study of the simulation. That was the reason why the ugly programmer of the function sampleN.scABEL() abstain from giving that numbers .— Regards, Detlew |
Helmut ★★★ Vienna, Austria, 2022-03-23 17:45 (956 d 13:29 ago) @ d_labes Posting: # 22866 Views: 3,345 |
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Dear Detlew, ❝ ❝ In coding the function
❝ ❝ Expanded limits : 0.7706 ... 1.2977 ❝ ❝ Upper scaling cap : CVwR > 0.5 ...❝ The Expanded limits are only valid if the CV's are exactly the assumed ones. ❝ They don't play any role during the simulations because the expansion applied depends on the CVwR of actual study, gradually different from study to study of the simulation. Of course, you are right. ❝ That was the reason why the ugly programmer of the function Don’t know which one of us is uglier. Beauty lies in the eye of the beholder. When it comes to coding, I’m notorious for producing ‘Spaghetti viennese’. I decided to give the expanded limits because in the simulations of the empiric Type I Error theta0 is set to the upper one.— 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 |
dshah ★★ India, 2022-03-23 19:08 (956 d 12:06 ago) @ Helmut Posting: # 22867 Views: 3,395 |
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Thank you Helmut! But my point for Bebac user was- He/She shall enhance the limit based on Swr and then calculate the subject size. I am still a fan of Dave's FARTSSIE and uses older version. Although I agree that fully replicate design will be more useful for Bebac user! On the other part, if the assumed PE is 0.9126-1.096, subject size of 40 could still be good considering no dropouts (Using Boss button). Regards, Divyen |
Helmut ★★★ Vienna, Austria, 2022-03-23 20:42 (956 d 10:32 ago) @ dshah Posting: # 22868 Views: 3,539 |
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Hi Divyen, ❝ But my point for Bebac user was- He/She shall enhance the limit based on Swr and then calculate the subject size. I am still a fan of Dave's FARTSSIE and uses older version. See this post and followings. Even if you are a fan of Dave (as I am), that’s not even wrong.
In your screenshot of FARTSSIE (which version?) I see limits of 75.00–133.33% for CV 35%. That’s not correct for ABEL, where the limits are 77.23–129.48% because $$\small{\eqalign{ s_\textrm{wR}&=\sqrt{\log_{e}(CV_\textrm{wR}^2+1)}\\ \left\{L,U\right\}&=100\exp(\mp 0.760\,\cdot s_\textrm{wR}) }}$$ For the conditions of the Gulf Cooperation Council1 (namely widened limits if \(\small{CV_\textrm{wR}>30\%}\)) you would need …
❝ On the other part, if the assumed PE is 0.9126-1.096, subject size of 40 could still be good considering no dropouts (Using Boss button). Nope (see above). Let’s be silent about the , please.
— 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 |
Helmut ★★★ Vienna, Austria, 2022-03-23 12:43 (956 d 18:31 ago) @ Bebac user Posting: # 22862 Views: 3,634 |
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Hi Bebac user, ❝ Partially replicated study,… If possible, avoid the partial replicate design. If you want only three periods (say, you are concerned about a potentially higher dropout-rate or larger sampled blood volume in a four-period full replicate design), use one of the two-sequence three-period full replicate designs (TRT|RTR or TRR|RTT). Why?
❝ ❝ ❝ ❝ ❝ ❝ But, I know that I can't use more than 40 volunteers in any BE study ❝ ❝ In these cases, what should I do ? Two options.
— 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 |
Brus ★ Spain, 2022-03-23 15:25 (956 d 15:48 ago) @ Bebac user Posting: # 22864 Views: 3,512 |
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Dear Bebac user, Why you can’t use more than 40 volunteers in any BE study? Does it appears in any guideline? Best regards, |