Achievwin ★ US, 20200928 01:58 (30 d 05:47 ago) Posting: # 21944 Views: 269 

Hello: share tools (R, SAS code and excel spreadsheet) for computing Sample size from ISCV for Parallel, 2x2, 3x3 and 4x4 BE study designs) also if we can compute ISCV or ANOVA CV from the confidence intervals. I truly appreciate your help. Regards, Achievwin. 
Helmut ★★★ Vienna, Austria, 20200928 09:31 (29 d 22:13 ago) @ Achievwin Posting: # 21946 Views: 225 

Hi Achievwin, » share tools (R, SAS code and excel spreadsheet) for computing Sample size from ISCV for Parallel, 2x2, 3x3 and 4x4 BE study designs) … The CV and T/Rratios are assumptions (or estimates if obtained from previous studies). Hence, sample size estimation (not computation or calculation), if you don’t mind. I recommend the package PowerTOST . For the implemented designs see here and there. You can also run scripts in the browser (see this post).If you are dealing with a higherorder design, I recommend the “Two at a Time” approach instead of “All at Once” (pooled ANOVA). See the vignette. That means to estimate the sample size of the study like for a 2×2×2 design. <nitpick> In a parallel design you get only the total (pooled) CV. If you want sumfink in M$ Excel, consider FARTSSIE which estimates the sample size based on the noncentral tdistribution. Note that the sample size for replicate designs is only approximate and for referencescaling wrong (since no algebraic solution exist and therefore, simulations are required). For 2×2×2 studies you can also implement approximations based on the central tdistribution.^{1} However, I don’t recommend that because in borderline cases the sample size will be higher than necessary:
Some SAS code based on the noncentral tdistribution is given by Jones and Kenward.^{2} AFAIK, no code for referencescaling is in the public domain. You are on your own – good luck and be prepared for extreme runtimes. » … also if we can compute ISCV or ANOVA CV from the confidence intervals. Sure – if you know also the sample size and design. For the underlying algebra see this presentation (slides 26–30). Implemented in PowerTOST ’s functions CVfromCI() / CI2CV() . See also the vignette. Example:
— Diftor heh smusma 🖖 Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 