Consider the horseshoe crab classification tree in Figure 11.1.

a. Sketch a plot of width against color. Based on the information at the terminal nodes, show the rectangular regions for which yˆ = 1. Compare to the regions for the simpler classification tree mentioned in Section 11.2.4 that uses λ = 0.07.

b. Constructing your own classification trees with these data for various λ values, investigate how the pruned tree depends on λ. Show the tree that seems most sensible to you.