library(DAAG) # has permutation test function

pr=c("to","to","c","c","c","c","c","c","c","c","c","to","c","to","c","c","to","to")
po=c("mc","mc","l","l","mc","l","l","l","l","l","l","mc","l","mc","l","l","mc","mc")
hw=c(22,15,7,10,10,15,14,10,20,20,5,14,20,10,5,10,15,10)
ex=c(5,15,4,4,10,5,0,6,5,7,1,6,90,3,3,5,0,14)
ex[13]=floor(median(ex)) # replace '90' with imputed value

# Exercise by polical idealogy
boxplot(ex~po,ylab="exercise hrs/week",names=c("liberal","moderate/conservative"))
twot.permutation(ex[po=="l"],ex[po=="mc"])
t.test(ex[po=="l"],ex[po=="mc"])
var.test(ex[po=="l"],ex[po=="mc"])

# Exercise by 2016 presidential choice
boxplot(ex~pr,ylab="exercise hrs/week",names=c("Clinton","Trump/Other"))
twot.permutation(ex[pr=="c"],ex[pr=="to"])
t.test(ex[pr=="c"],ex[pr=="to"])
var.test(ex[pr=="c"],ex[pr=="to"])

# Homework by polical idealogy
boxplot(hw~po,ylab="homework hrs/week",names=c("liberal","moderate/conservative"))
twot.permutation(hw[po=="l"],hw[po=="mc"])
t.test(hw[po=="l"],hw[po=="mc"])
var.test(hw[po=="l"],hw[po=="mc"])