pdf("ex0505.pdf")

# Read in data from ASCII formatted (Fixed With File)

ex0505dat <- read.fwf("http://www.stat.ufl.edu/~winner/data/biostat/ex0505.dat", width=c(8,8,8,8), 
        col.names=c("trt","death","trt_r","death_r"))


# Create a dataset (frame) from input data

ex0505 <- data.frame(ex0505dat)

# Attach the dataset for analysis 

attach(ex0505)

# Obtain crosstabulation of trt and death

freqtd <- table(trt, death)

freqtd

# Obtain the probabilities of death for each trt group
# Note that death is labelled "0" and "1", and we are modelling probability of "1"
# Note that trt is labelled "0" and "1", and we are modelling P(death=1|trt=1)/p(death=1|trt=0)

probrow1 <- freqtd[1,2]/(freqtd[1,1]+freqtd[1,2])

probrow2 <- freqtd[2,2]/(freqtd[2,1]+freqtd[2,2])

probrow1

probrow2

# Obtain P-value based on Fisher's exact test (This gives a 2-sided P-value)

fisher.test(freqtd)




dev.off()