A graphical illustration of the bootstrap approach on a small sample containing n =3 observations. Each bootstrap data set contains n observations, sampled with replacement from the original data set. Each bootstrap data set is used to obtain an estimate of α (G. James et al., An Introduction to Statistical Learning: with Applications in R , p.190) Examples with a simple linear regression model 1. Nonparametric Bootstrap with hand-written function 2. Nonparametric Bootstrap using "boot" function