Review for NeurIPS paper: Model Class Reliance for Random Forests

Neural Information Processing Systems 

Weaknesses: The main concern I have with the paper is in the argument that the estimator does in fact converge to MCR and MCR- for random forests. Section 4.1 provides an argument that, as the number of trees goes to infinity, each tree will be replaced with one from its Rashomon set that is maximally dependent on X1 (when doing the MCR procedure). In finite samples, and with a finite number of trees, there are reasons to doubt whether this method provides consistent estimation of MCR for the random forest as a whole. The favorable generalization properties of random forests are known to be derived from the diversity of trees in the ensemble: a well known result of Breiman is that the generalization error decreases as the correlation of the residuals from the trees decreases. While the predictions of a tree and its surrogate may be identical for a given dataset, replacing a tree with the surrogate seems that it may decrease the expected generalization error of the tree as a whole.