From Points to Coalitions: Hierarchical Contrastive Shapley Values for Prioritizing Data Samples
Canran Xiao, Jiabao Dou, Zhiming Lin, Zong Ke, Liwei Hou
TL;DR
This work addresses the computational bottleneck and geometry-insensitivity of classical data Shapley valuation by introducing Hierarchical Contrastive Data Valuation (HCDV). HCDV combines a geometry-preserving contrastive embedding with a coarse-to-fine hierarchical partition of the data and local Shapley computations that propagate budgets downward, achieving scalable, multiscale data valuation. The authors provide theoretical guarantees on approximate Shapley properties, concentration, and top-k surrogate regret, and demonstrate substantial accuracy gains, runtime reductions, and practical benefits in augmentation filtering, streaming updates, and data marketplace pricing across diverse benchmarks. The approach enables geometry-aware, scalable, and interpretable data valuation with strong empirical and theoretical support for real-world data-centric ML systems.
Abstract
How should we quantify the value of each training example when datasets are large, heterogeneous, and geometrically structured? Classical Data-Shapley answers in principle, but its O(n!) complexity and point-wise perspective are ill-suited to modern scales. We propose Hierarchical Contrastive Data Valuation (HCDV), a three-stage framework that (i) learns a contrastive, geometry-preserving representation, (ii) organizes the data into a balanced coarse-to-fine hierarchy of clusters, and (iii) assigns Shapley-style payoffs to coalitions via local Monte-Carlo games whose budgets are propagated downward. HCDV collapses the factorial burden to O(T sum_{l} K_{l}) = O(T K_max log n), rewards examples that sharpen decision boundaries, and regularizes outliers through curvature-based smoothness. We prove that HCDV approximately satisfies the four Shapley axioms with surplus loss O(eta log n), enjoys sub-Gaussian coalition deviation tilde O(1/sqrt{T}), and incurs at most k epsilon_infty regret for top-k selection. Experiments on four benchmarks--tabular, vision, streaming, and a 45M-sample CTR task--plus the OpenDataVal suite show that HCDV lifts accuracy by up to +5 pp, slashes valuation time by up to 100x, and directly supports tasks such as augmentation filtering, low-latency streaming updates, and fair marketplace payouts.
