A Probabilistic Method for Inferring Preferences from Clicks
Katja Hofmann‚ Shimon Whiteson and Maarten de Rijke
Implicit feedback, such as clicks on documents in a result list, is an increasingly popular alternative to explicit relevance judgments. Previous work has shown that so-called interleaved comparison methods can utilize click data to detect small differences between rankers and can be applied to learn ranking functions online. In this paper, we analyze three existing interleaved comparison methods and find that they are all either biased or insensitive to some differences between rankers. To address these problems, we present a new method based on a probabilistic interleaving process. We derive an unbiased estimator of comparison outcomes and show how marginalizing over possible comparison outcomes given the observed click data can make this estimator even more effective. We validate our approach using a recently developed simulation framework based on a learning to rank dataset and a model of click behavior. Our experiments confirm the results of our analysis and show that our method can reliably identify the preferred ranker using significantly less click data than existing methods.