arXiv AI

Leaf Values as Coordinates: Exact Contrastive Explanation for Gradient-Boosted Ensembles

The paper proposes treating leaf values of a gradient‑boosted ensemble as coordinates in ℝ^M, turning the model into a linear function over these coordinates. This perspective allows exact contrastive explanations: the difference between two instances is a vector that is zero wherever they share a leaf, so the gap is attributed to a few coordinates linked to specific tree splits. The authors build a recourse method based on this representation, achieving near‑perfect reconstruction of the model’s decision and demonstrating competitive performance on tabular datasets, especially when recommendations are limited to actionable changes.

arXiv AI
Sep 2

Measuring consistency via ensemble margin and local prediction variability: Auditing decision systems in the presence of predictive multiplicity

The paper introduces a new consistency criterion for auditing decision systems that combines ensemble margin with local prediction variability to address predictive multiplicity, or the Rashomon effect. It shows that finite ensembles converge to the expected model’s consistency score as ensemble size and sample count grow, and demonstrates that ensembling models from the Rashomon set reduces unchecked incorrect predictions while keeping diversions moderate. Experiments on transformer and fine‑tuned language models for NLP and tabular classification confirm the method’s effectiveness and stronger alignment with existing multiplicity metrics.

By Sinjini Banerjee, Tim Marrinan, Anand D. Sarwate