Understanding QQ plots

## Try distributions like rchisq, rt, runif, rf to view its heavy, or light, left, or right tail.


n <- 30;
ry <- rnorm(n);
qqnorm(ry);qqline(ry);
max(ry)
min(ry)
##view and guess what are x(s) and y(s)
I <- rep(1,n);
qr <- ((ry%*%t(I) > I %*% t(ry))+.5*(ry %*% t(I) == I%*%t(ry)))%*%I *(1/n);##qr are the sample quantiles
points(qr,ry,col="blue"); ##to view the fact, try the following
points(qr,qr*0,col="green",pch="|");
rx <- qnorm(qr);
points(rx,ry,col="red",pch="O");
##Red O(s) circle black o(s) exactly.

Leave a Reply

Your email address will not be published. Required fields are marked *