Title
A General Framework for Counterfactual Learning-to-Rank
Abstract
Implicit feedback (e.g., click, dwell time) is an attractive source of training data for Learning-to-Rank, but its naive use leads to learning results that are distorted by presentation bias. For the special case of optimizing average rank for linear ranking functions, however, the recently developed SVM-PropRank method has shown that counterfactual inference techniques can be used to provably overcome the distorting effect of presentation bias. Going beyond this special case, this paper provides a general and theoretically rigorous framework for counterfactual learning-to-rank that enables unbiased training for a broad class of additive ranking metrics (e.g., Discounted Cumulative Gain (DCG)) as well as a broad class of models (e.g., deep networks). Specifically, we derive a relaxation for propensity-weighted rank-based metrics which is subdifferentiable and thus suitable for gradient-based optimization. We demonstrate the effectiveness of this general approach by instantiating two new learning methods. One is a new type of unbiased SVM that optimizes DCG - called SVM PropDCG - and we show how the resulting optimization problem can be solved via the Convex Concave Procedure (CCP). The other is Deep PropDCG, where the ranking function can be an arbitrary deep network. In addition to the theoretical support, we empirically find that SVM PropDCG significantly outperforms existing linear rankers in terms of DCG. Moreover, the ability to train non-linear ranking functions via Deep PropDCG further improves performance.
Year
DOI
Venue
2019
10.1145/3331184.3331202
Proceedings of the 42nd International ACM SIGIR Conference on Research and Development in Information Retrieval
Keywords
Field
DocType
counterfactual inference, learning to rank, presentation bias
Econometrics,Learning to rank,Information retrieval,Computer science,Counterfactual thinking,Discounted cumulative gain
Conference
ISBN
Citations 
PageRank 
978-1-4503-6172-9
21
0.65
References 
Authors
0
4
Name
Order
Citations
PageRank
Aman Agarwal1603.91
Kenta Takatsu2210.65
Ivan Zaitsev3381.21
Thorsten Joachims4173871254.06