Decision-Path Patterns as Tree Reliability Signals: Path-based Adaptive Weighting for Random Forest Classification
Youngjoon Park
Abstract
Random forests aggregate tree votes by simple majority, treating all trees as equally informative. We observe that the topological pattern along each tree's root-to-leaf decision path -- where and how often the dominant class label flips along it -- carries a signal of tree reliability that is exploitable for per-sample reweighting. The naive use of this signal is structurally confounded with the predicted class, so we propose a class-conditional ratio weighting that guarantees zero expected class bias by construction. On 30 binary classification benchmarks under a shared-forest, shared-split protocol with 30 repeats, the proposed method is the only one among four compared schemes -- RF, weighted RF, KNORA-Eliminate, KNORA-Union -- to yield a statistically significant accuracy improvement over RF (Wilcoxon p = 0.018), while the three alternatives all fail to do so (p > 0.5). It is also the only scheme without majority-recall regressions, with minority-recall regressions limited to 3/30 datasets -- a one-sided loss to which classical dynamic ensemble selection methods are susceptible. The gain is robust across forest sizes from 100 to 1000 trees.
Topics
Classified with taxonomy v2 on Wed, 2 Sept 2026.