提出轻量级方法Linear-PAL,解决电商排序中的位置偏差问题。
Linear-PAL: A Lightweight Ranker for Mitigating Shortcut Learning in Personalized, High-Bias Tabular Ranking
- 通过结构约束和正则化抑制深度模型的捷径学习
- 在420万数据上实现0.7626的去偏相关性AUC,训练快43倍
- 适合需要高频重训练的个性化实时推荐场景
在电商排序中,用户隐式反馈受位置偏差严重影响——用户更倾向于点击排名靠前的项目,而非其相关性。尽管深度学习模型(如双塔网络)是主流去偏方法,我们发现,在高偏差环境下,最先进的深度集成模型会因过拟合排名信号而产生捷径学习,导致排序质量下降,尽管预测准确率很高。为此,我们提出轻量级框架Linear-PAL,通过显式特征组合与强正则化实现去偏。同时引入向量化整数哈希技术,将字符串操作替换为O(N)的向量化运算。在包含420万样本的大规模数据集上,Linear-PAL实现了帕累托占优:去偏排序质量(相关性AUC:0.7626 vs. 0.6736)优于深度集成模型,且训练延迟降低43倍(40秒 vs. 1762秒)。该效率支持高频重训练,使系统能捕捉用户特定的新兴市场趋势,实现实时个性化排序。
原文摘要 · Abstract (English)
In e-commerce ranking, implicit user feedback is systematically confounded by Position Bias -- the strong propensity of users to interact with top-ranked items regardless of relevance. While Deep Learning architectures (e.g., Two-Tower Networks) are the standard solution for de-biasing, we demonstrate that in High-Bias Regimes, state-of-the-art Deep Ensembles suffer from Shortcut Learning: they minimize training loss by overfitting to the rank signal, leading to degraded ranking quality despite high prediction accuracy. We propose Linear Position-bias Aware Learning (Linear-PAL), a lightweight framework that enforces de-biasing through structural constraints: explicit feature conjunctions and aggressive regularization. We further introduce a Vectorized Integer Hashing technique for feature generation, replacing string-based operations with $O(N)$ vectorized arithmetic. Evaluating on a large-scale dataset (4.2M samples), Linear-PAL achieves Pareto Dominance: it outperforms Deep Ensembles in de-biased ranking quality (Relevance AUC: 0.7626 vs. 0.6736) while reducing training latency by 43x (40s vs 1762s). This computational efficiency enables high-frequency retraining, allowing the system to capture user-specific emerging market trends and deliver robust, personalized ranking in near real-time.
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