Summary

In this chapter, we learned how to evaluate regression models. We used residuals to calculate the MAE and RMSE, and then used those metrics to compare models. We also learned about RFE and how it can be used for feature selection. We were able to see the effect of feature elimination on the MAE and RMSE metrics and relate it to the robustness of the model. We used these concepts to verify that the intuitions about the importance of the "number of competitors" feature were wrong in our case study. Finally, we learned about tree-based regression models and looked at how they can fit some of the non-linear relationships that linear regression is unable to handle. We saw how random forest models were able to perform better than regression tree models and the effect of increasing the maximum tree depth on model performance. We used these concepts to model the spending behavior of people with respect to their age.

In the next chapter, we will learn about classification...