Decision trees
Decision trees are tree-like graphs that model a decision. They are analogous to the parlor game Twenty Questions. In Twenty Questions, one player, called the answerer, chooses an object but does not reveal the object to the other players, who are called questioners. The object should be a common noun, such as "guitar"or "sandwich", but not "1969 Gibson Les Paul Custom" or "North Carolina". The questioners must guess the object by asking as many as twenty questions that can be answered with "yes", "no", or "maybe". An intuitive strategy for questioners is to ask questions of increasing specificity; asking"is it a musical instrument?" as the first question will not efficiently reduce the number of possibilities, on average. The branches of a decision tree specify the shortest sequences of featuresthat can be examined in order to estimate the value of a response variable. To continue the analogy, in Twenty Questions, the questioner and the answerer all have knowledge of the...