QQ plot is an essential tool in GWAS. Here I would like to organize some basic ideas of QQ plot and its application in GWAS. What is QQ plot? QQ plot is a graphic tool for testing if a set of data came from some theoretical distribution. Examples in R qqnorm Test if a set of data comes from normal distribution. In R, qqnorm(trees$Height) qqplot Create a QQ plot for any …