library(ISLR)
library(boot)
alpha.fn=function(data,index){
X=data$X[index]
Y=data$Y[index]
return((var(Y)-cov(X,Y))/(var(X)+var(Y)-2*cov(X,Y)))}
#"renaming my variables to fit the alpha function"
Xy$X=Xy$X1;
Xy$Y=Xy$y;
set.seed(1)
alpha.fn(Xy,sample(100,100,replace=T))
boot(Xy,alpha.fn,R=1000)