Modern search engine result pages often provide immediate value to users and organize information in such a way that it is easy to navigate. The core ranking contributes to this and so do result snippets, smart organization of result blocks and extensive use of one-box answers or side panels. While they are useful to the user and help search engines to stand out, such features present two big challenges for evaluation. First, the presence of such elements on a search engine result page (SERP) may lead to the absence of clicks, which is, however, not related to dissatisfaction, so-called “good abandonments.” Second, the non-linear layout and visual difference of SERP items may lead to a non-trivial sequence of the user’s attention, which is not captured by existing evaluation metrics.
In this paper we propose a model of user behavior on a SERP that jointly captures click behavior, user’s attention and satisfaction, the CAS model, and demonstrate that it gives more accurate predictions of user actions and self- reported satisfaction than existing models based on clicks. We use the CAS model to build a novel evaluation metric that can be applied to non-linear SERP layouts and that account for the utility that users obtain directly on a SERP. We demonstrate that this metric shows better agreement with user-reported satisfaction than conventional evaluation metrics.