# R-program for Extra Exercise 22

# from Exercise 10.33
child <- read.csv("r:/Chapter 10/ex10_033.csv")
cor.test (~ crp+retinol, data=child, method="spearman")
# manual calculation of Spearman's rho, for demonstration purposes
child$rankret <- rank(child$retinol)
child$rankcrp <- rank(child$crp)
cor.test (~ rankcrp+rankret, data=child, method="pearson")

# from Exercise 10.7
golf <- read.csv("r:/Chapter 2/ex02_002.csv")
cor.test (~ round1+round2, data=golf, method="spearman")
cor.test (~ round1+round2, data=golf[golf$player!=8,], method="spearman")
# extra question
cor.test (~ round1+round2, data=golf[golf$player!=7,], method="spearman")
cor.test (~ round1+round2, data=golf[golf$player!=8 & golf$player!=7,], method="spearman")

# note: more exact p-values for testing Spearman's rho equal to zero exist in R
# see cor.test help page