8.4 Interpretation of results: regression tree (Hitters data)

1. Years is the most important factor in determining Salary: players with less experience earn lower salaries than more experienced players.

2. Given that a player is less experienced, the number of Hits that he made in the previous year seems to play little role in his Salary

3. But among players who have been in the major leagues for 5 or more years, the number of Hits made in the previous year does affect Salary: players who made more Hits last year tend to have higher salaries

4. This is surely an over-simplification, but compared to a regression model, it is easy to display, interpret and explain