R-Code for Power in 2×2 Cross-over [🇷 for BE/BA]
Dear all,
I am a amateur in BA/BE area and trying to learn from this forum. I would appreciate if anyone kindly answer few of my queries for the r-code used to reproduce Fig.1c by Diletti et al. (1991).
Q1) If it is 2x2 cross-over study, test and ref drug would be given only once. Can we get true intra-subject co-efficient of variance (CV)from 2x2 cross-over study?
Q2) If it is possible to calculate the intra-subject co-efficient of variance (CV)from 2x2 cross-over study, is this value coming from ref drug only?
Q3) What is the equation for calculating this intra-subject co-efficient of variance (CV)?
Q4) In the equation "s = sqrt(2)*sigmaW", what 's' stands for? why '2' is square-rooted?
Q5) I have used the following r-code for calculating point estimate and CI limit of AUC.
Can I calculate CV by the following equation?
CV=SD/(exp(mD))
Based on my understanding, this my calculated CV is not the same as the 'CV' that represent intra-subject co-efficient of variance used to reproduce Fig.1c by Diletti et al. (1991)
what code/formula should I use if I want to calculate intra-subject co-efficient of variance?
Regards
KDA
I am a amateur in BA/BE area and trying to learn from this forum. I would appreciate if anyone kindly answer few of my queries for the r-code used to reproduce Fig.1c by Diletti et al. (1991).
Q1) If it is 2x2 cross-over study, test and ref drug would be given only once. Can we get true intra-subject co-efficient of variance (CV)from 2x2 cross-over study?
Q2) If it is possible to calculate the intra-subject co-efficient of variance (CV)from 2x2 cross-over study, is this value coming from ref drug only?
Q3) What is the equation for calculating this intra-subject co-efficient of variance (CV)?
Q4) In the equation "s = sqrt(2)*sigmaW", what 's' stands for? why '2' is square-rooted?
Q5) I have used the following r-code for calculating point estimate and CI limit of AUC.
A1 <- data$AUC[which(data$TRT=="R1" & data$PER==1)]
B2 <- data$AUC[which(data$TRT=="R2" & data$PER==2)]
B1 <- data$AUC[which(data$TRT=="R2" & data$PER==1)]
A2 <- data$AUC[which(data$TRT=="R1" & data$PER==2)]
AB <- log(B2)-log(A1)
BA <- log(B1)-log(A2)
n1 <- length(AB)
mAB <- mean(AB)
vAB <- var(AB)
n2 <- length(BA)
mBA <- mean(BA)
vBA <- var(BA)
mD <- mean(log(c(B1,B2))) - mean(log(c(A1,A2)))
MSE <- (((n1-1)*vAB + (n2-1)*vBA)/(n1+n2-2))/2
alpha <- 0.05
lo <- mD - qt(1-alpha,n1+n2-2)*sqrt(MSE)*sqrt((1/(2*n1) + 1/(2*n2)))
hi <- mD + qt(1-alpha,n1+n2-2)*sqrt(MSE)*sqrt((1/(2*n1) + 1/(2*n2))
PE <- 100*exp(mD)
90_CI_Lower <- 100*exp(lo)
90_CI_Higher <- 100*exp(hi)
SE <- sqrt(MSE)*sqrt((1/(2*n1) + 1/(2*n2)))
SD <- sqrt(MSE)
Can I calculate CV by the following equation?
CV=SD/(exp(mD))
Based on my understanding, this my calculated CV is not the same as the 'CV' that represent intra-subject co-efficient of variance used to reproduce Fig.1c by Diletti et al. (1991)
what code/formula should I use if I want to calculate intra-subject co-efficient of variance?
Regards
KDA
Complete thread:
- R-Code for Power in 2×2 Cross-over Helmut 2006-12-28 21:33 [🇷 for BE/BA]
- Power in Diletti's sample size table Helmut 2007-01-01 23:59
- Approximate Power Helmut 2007-01-06 15:17
- Power Calculation for replicate crossover design mathews 2008-04-03 13:19
- Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
- Power Calculation for replicate crossover design mathews 2008-04-04 13:21
- Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
- Exact Power Helmut 2009-09-25 19:20
- Exact Power ElMaestro 2009-09-27 23:27
- Software validation Helmut 2009-09-28 15:21
- All the important answers are here! ElMaestro 2009-09-28 19:12
- All the important answers are here! Helmut 2009-09-28 19:52
- All the important answers are here! ElMaestro 2009-09-28 20:18
- All the important answers are here! yjlee168 2009-09-28 21:30
- All the important answers are here! Helmut 2009-09-28 23:18
- 42! SASophylistic power oracle d_labes 2009-09-29 13:37
- Al Gore Rhythms Helmut 2009-09-29 14:52
- Al Gore Rhythms ElMaestro 2009-09-29 18:14
- Al Gore Rhythms yjlee168 2009-09-29 23:55
- Al Gore Rhythms Helmut 2009-09-29 14:52
- 42! SASophylistic power oracle d_labes 2009-09-29 13:37
- All the important answers are here! yjlee168 2009-09-29 23:49
- All the important answers are here! Helmut 2009-09-28 23:18
- All the important answers are here! Helmut 2009-09-28 19:52
- All the important answers are here! ElMaestro 2009-09-28 19:12
- Software validation Helmut 2009-09-28 15:21
- Exact Power ElMaestro 2009-09-27 23:27
- Power Calculation for replicate crossover design mathews 2008-04-03 13:19
- Approximate Power Helmut 2007-01-06 15:17
- R-Code for Power in 2×2 Cross-overKDA 2019-01-23 04:24
- R-Code for Power in 2×2 Cross-over Ohlbe 2019-01-27 18:24
- R-Code for Power in 2×2 Cross-over Brus 2021-12-02 15:00
- R-Code for Power in 2×2 Cross-over ElMaestro 2021-12-02 15:15
- R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 17:30
- R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 16:57
- R-Code for Power in 2×2 Cross-over ElMaestro 2021-12-02 15:15
- Power in Diletti's sample size table Helmut 2007-01-01 23:59