8.3 Terminology:

• Overall, the tree stratifies or segments the players into three regions of predictor space:

  • R1 = {X | Years< 4.5}

  • R2 = {X | Years>=4.5, Hits<117.5}

  • R3 = {X | Years>=4.5, Hits>=117.5}

where R1, R2, and R3 are terminal nodes (leaves) and green lines (where the predictor space is split) are the internal nodes

• The number in each leaf/terminal node is the mean of the response for the observations that fall there