# R-program for Supplementary Exercise 3.40 of IPS7e
# showing code for the third method described in the solution

women <- read.csv("r:/Chapter 3/ex03_040.csv")
women.sorted <- women[order(women$excw),]
women.sorted$block <- rep(1:5, each=4)
set.seed(22092015)
women.sorted$random <- runif(20)
# data frame sorted according to random within blocks
women.sorted2 <- women.sorted[order(women.sorted$block, women.sorted$random),]
women.sorted2$tx <- rep(c("A","B","C","D"),5)
women.sorted2