pharm07 ☆ India, 2022-05-03 13:23 (918 d 20:39 ago) Posting: # 22953 Views: 3,679 |
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Hi, Can anyone guide, how to calculate sample size for NTI category drug using R software? I have primary information as ISCV. Edit: Category changed; see also this post #1. [Helmut] — Regards, pharm07 |
dshah ★★ India, 2022-05-03 15:04 (918 d 18:57 ago) @ pharm07 Posting: # 22954 Views: 3,273 |
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Helmut ★★★ Vienna, Austria, 2022-05-03 16:38 (918 d 17:23 ago) @ pharm07 Posting: # 22955 Views: 3,014 |
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Hi pharm07, as suggested by Dshah, assuming a T/R-ratio of 0.975 and a CV of 0.1:
More details and examples in this article. — 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 |
pharm07 ☆ India, 2022-05-04 10:08 (917 d 23:54 ago) @ Helmut Posting: # 22958 Views: 3,113 |
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HI Helmut, Thanks for the information. After installing package from local file, (https://cloud.r-project.org/) response in R console : > utils:::menuInstallLocal() package ‘PowerTOST’ successfully unpacked and MD5 sums checked Even after this step i am not able to attach power tost to the library. After this step i can able to do further. [Using R 4.2.0] Please suggest. — Regards, pharm07 |
Helmut ★★★ Vienna, Austria, 2022-05-04 12:33 (917 d 21:28 ago) @ pharm07 Posting: # 22959 Views: 3,050 |
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Hi pharm07, ❝ response in R console : > ❝ OK, so you ended up as shown there (example for Power2Stage ).❝ Even after this step i am not able to attach power tost to the library. Package ≠ library. Not sure what you mean, can you explain? ❝ After this step i can able to do further. OK. ❝ Please suggest. Copy one of the examples of my previous post and paste it to the console. If you want to go for the FDA’s method, just a one-liner because theta0 = 0.975 , design = "2x2x4" , and targetpower = 0.8 are defaults of the function. Hence, you have to specify only the CV :
Since this is a four-period design, you may want to increase the sample size to compensate for a potential loss in power due to dropouts.
If you are confused, see there. — 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 |
pharm07 ☆ India, 2022-05-04 16:54 (917 d 17:08 ago) @ Helmut Posting: # 22961 Views: 3,061 |
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Hi, ❝ Package ≠ library. Not sure what you mean, can you explain? I meant i was not able to execute library(PowerTOST) command. Now, i am able to estimate sample size..! Your guidance is much more appreciable. Thanks.. — Regards, pharm07 |
pharm07 ☆ India, 2022-05-11 07:30 (911 d 02:32 ago) @ pharm07 Posting: # 22968 Views: 2,869 |
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Hi Helmut, Let me understand again by looking following framework, Following data is available with me, Target power : eg, 0.8, .85, 0.9, CwT,CwR,sigWT,SigWR,theta0,theta1,theta2. i want to estimate sample size for low to moderate NTID. Also to estimate sample size by assuming 30 & 40 % dropout rate. I have gone through the examples. Sometimes error comes as its beyond implied limit. Heteroscedasticity can be challenging for me as T>R. Can you check and verify if i am using correct programming. This Example. — Regards, pharm07 |
Helmut ★★★ Vienna, Austria, 2022-05-11 15:19 (910 d 18:42 ago) @ pharm07 Posting: # 22970 Views: 2,842 |
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Hi pharm07, ❝ Let me understand again by looking following framework, ❝ Following data is available with me, ❝ Target power : eg, 0.8, .85, 0.9, CwT,CwR,sigWT,SigWR,theta0,theta1,theta2. Although you could give values of theta1 and theta2 , for the FDA keep the defaults of 0.8 and 1.25 (i.e., don’t specify anything): Additionally to passing RSABE and the variance-comparison you must pass conventional ABE.❝ i want to estimate sample size for low to moderate NTID. More examples are given there. ❝ Also to estimate sample size by assuming 30 & 40 % dropout rate. See the two supportive functions in the section about dropouts in the named article. ❝ I have gone through the examples. Sometimes error comes as its beyond implied limit. That’s possible if you specify a low or high theta0 . Background: $$\eqalign{s_0&=0.1\tag{1}\\\theta_\text{s}&=\frac{\log_e(1/0.9)}{s_0}\approx1.053605\ldots\\ \left\{\theta_{\text{s}_1},\theta_{\text{s}_2}\right\}&=\exp(\mp\theta_\text{s}\cdot s_\text{wR}), }$$ where \(\small{s_0}\) is the regulatory switching condition, \(\small{\theta_\text{s}}\) the regulatory constant, and finally \(\small{\left\{\theta_{\text{s}_1},\theta_{\text{s}_2}\right\}}\) are the implied limits. Say, you assume \(\small{CV_\text{wR}=0.1}\). Since $$s_\text{wR}=\sqrt{\log_e(CV_\text{wR}^2+1)}\tag{2}$$ and by using \(\small{(1)}\) you end up with $$\left\{\theta_{\text{s}_1},\theta_{\text{s}_2}\right\}=\left\{0.9002,1.1108\right\}.\tag{3}$$ In other words, for this \(\small{CV_\text{wR}}\) any theta0 outside these limits cannot work. That’s by design:
Would you want to estimate a sample size for conventional ABE with a T/R-ratio outside 80–125%? Try:
For NTIDs the FDA requires stricter batch-release spec’s (±5% instead of the common ±10%). Therefore, theta0 = 0.975 is the default of this function. I would not go below 0.95 unless the CV is relatively high (no scaling if \(\small{CV_\text{wR}\geq0.2142}\)).❝ Heteroscedasticity can be challenging for me as T>R. Yes, you are not alone. ❝ Can you check and verify if i am using correct programming. I can’t till you post an example which you consider problematic. — 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 |
pharm07 ☆ India, 2022-05-18 07:18 (904 d 02:43 ago) @ Helmut Posting: # 22995 Views: 2,768 |
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Hi Helmut, ❝ Although you could give values of OK. Noted. ❝ More examples are given there. OK. I referred these examples. ❝ See the two supportive functions in the section about dropouts in the named article. Ok, I have pasted one example which i seems to be work upon. ❝ That’s possible if you specify a low or high OK. ❝ Yes, you are not alone. ❝ I can’t till you post an example which you consider problematic. Please see below example, Note : CV is not in scalar form.' sampleN.NTID(CV = c(0.045,0.07), theta0 = 0.95, targetpower = 0.9) # with 30% DO rate, # as CV was specified as Vector, # is following steps right? balance <- function(n, n.seq) { Kindly guide me with this example, i want to check whether i am making a mistake or not. — Regards, pharm07 |
Helmut ★★★ Vienna, Austria, 2022-05-18 16:30 (903 d 17:32 ago) @ pharm07 Posting: # 23002 Views: 4,328 |
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Hi pharm07, ❝ Kindly guide me with this example, i want to check whether i am making a mistake or not. In your second script you forgot to state theta0 = 0.95 . Hence, the default theta = 0.975 was employed.library(PowerTOST) — 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 |
pharm07 ☆ India, 2022-05-19 07:36 (903 d 02:26 ago) @ Helmut Posting: # 23003 Views: 3,025 |
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Hi Helmut, I got it..! Thanks for the interaction and time — Regards, pharm07 |