FDA's HVD SAS Code / Standard Error / CV [Regulatives / Guidelines]
Here is the SAS code for the analysis of ABE with fully replicate design data.
CLASSES SEQ SUBJ PER TRT;
MODEL Y = SEQ PER TRT/ DDFM=SATTERTH;
RANDOM TRT/TYPE=FA0(2) SUB=SUBJ G;
ESTIMATE 'T vs. R' TRT 1 -1/CL ALPHA=0.1;
Q2: When should I write 1 -1 and when should I write -1 1 in estimate statements?
Here is the covariance output from SAS
Covariance Parameter Estimates
Cov Parm Subject Group Estimate
FA(1,1) subject 0.2001
FA(2,1) subject 0.1263
FA(2,2) subject 0.1507
Residual subject formulation Ref 0.01495
Residual subject formulation Test 0.03265
G(1,1) = 0.04005, G(2,1)=G(1,2)=0.02527, G(2,2)=0.03866
In replicate design, the intra-subject variabilities are still calculated from the residuals as in a 2-way crossover, using:
IntraCV_T = 100%*sqrt(exp(sig_WT^2)-1)
IntraCV_R = 100%*sqrt(exp(sig_WR^2)-1)
The data include 10 subjects and 5 in seq 1 and 5 in seq2. This is a 2*2*4, 2 sequence 2 treatment and 4 period design, 90% CI of T/R is (0.8450984199, 1.104975448) and point estimate is 0.9663400049.
I tried to use CVfromCI function from R package PowerTOST to calculate CV, and here is my r code:
100*CVfromCI(alpha=0.05, lower=0.8450985339, upper=1.104975299, n=c(5,5), design="2x2x4")
and I get CV = 25.24456.
Q3: Is this CV a pooled CV? If I want to get CVwt and CVwr based on confidence interval, how can I do it using R package
Q4: I try to use the formula 100%*sqrt(exp(sig_W^2)-1) where sig_w^2 = (sig_wt^2+sig_wr^2)/2 to get the same CV(25.24456) based on the covariance output above, but the value is different. Is my calculation wrong? If so, can anyone please tell me the right way to get same CV?
Edit: Code and results BBCoded; see also this post #10. [Helmut]
- FDA's HVD SAS Code / Standard Error / CVj_kevin 2022-12-08 09:41 [Regulatives / Guidelines]
- FDA's HVD SAS Code / Standard Error / CV Helmut 2022-12-08 12:09