让语言模型与随机森林互相学习,提升医疗数据预测效果。
Reciprocal Co-Training (RCT): Coupling Gradient-Based and Non-Differentiable Models via Reinforcement Learning

- 用强化学习搭建双向反馈,让可梯度优化的模型和不可微分模型协同训练。
- 在三个医疗数据集上,双方模型性能均显著提升,最高准确率提高4.2%。
- 适合需要融合文本与表格数据的医学预测场景,尤其对模型融合新手友好。
语言模型(LM)与传统机器学习方法在预测建模中各有优势,但因表示方式和训练范式差异难以有效结合:LM依赖文本数据的梯度优化,而随机森林(RF)采用非可微特征划分。本文提出一种互惠协同训练框架(RCT),通过强化学习将LM与RF耦合,形成迭代反馈循环,使双方模型基于对方信号持续优化。将表格数据转化为标准化文本表示输入LM,其嵌入向量扩充RF特征空间;同时,经校准的RF概率输出作为奖励信号,指导LM的强化学习更新。在三个医疗数据集上的实验表明,使用领域适配的临床编码器(ClinicalBERT)和更大指令微调模型(Qwen2-7B-Instruct)时,双模型性能均有稳定提升。消融实验显示,迭代精炼、混合奖励设计与维度控制共同促成性能增益。SHAP分析证实,LM生成的表示是影响RF预测最重要的输入之一。该框架为不同模型家族通过双向适应相互赋能提供通用机制。
原文摘要 · Abstract (English)
Language models (LMs) and classical machine learning methods offer complementary strengths for predictive modeling, yet their fundamentally different representations and training paradigms hinder effective integration: LMs rely on gradient-based optimization over textual data, whereas models such as Random Forests (RF) employ non-differentiable feature partitioning. This work introduces a reciprocal co-training framework that couples an LM with an RF classifier via reinforcement learning, creating an iterative feedback loop in which each model improves using signals from the other. Tabular data are reformulated into standardized textual representations for the LM, whose embeddings augment the RF feature space, while calibrated RF probability estimates provide feedback signals that guide reinforcement learning updates of the LM. Experiments across three medical datasets, evaluated with both a domain-adapted clinical encoder (ClinicalBERT) and a larger instruction-tuned language model (Qwen2-7B-Instruct), demonstrate consistent performance gains for both model components. Ablation analyses indicate that iterative refinement, hybrid reward design, and dimensionality control jointly contribute to these gains. SHAP analysis further confirms that LM-derived representations are among the most important inputs to the RF predictions. The proposed framework provides a general mechanism that allows incompatible model families to leverage each other's strengths through bidirectional adaptation.
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