pdf("ex0304.pdf")

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

ex0304dat <- read.fwf("http://www.stat.ufl.edu/~winner/data/biostat/ex0304.dat", width=c(8,8), col.names=c("group","auc"))

# Create a dataset (frame) from input data

ex0304 <- data.frame(ex0304dat)

# Attach the dataset for analysis 

attach(ex0304)

# Conduct the t-test, auc is the dependent variable, group is independent variable
# var.equal=T  (true) says to use the procedure vased on the pooled standard deviation (equal variance case)

t.test(auc~group, var.equal=T)

# Conduct the Wilcoxon rank-sum test, auc is the dependent variable, group is independent variable
# Note that the W statistic is the rank-sum for group 1 minus the smallest value it could
#   take on. So in texts notation:  W=T1-(1+2+...+n1). P-values are not effected by the transformation

wilcox.test(auc~group)


# Obtain a plot of auc (y-axis) versus group (x-axis)

plot(group,auc)

dev.off()