Towards Nuanced System Evaluation Based on Implicit User Expectations

Abstract

Information retrieval systems are often evaluated through the use of effectiveness metrics. In the past, the metrics used have corresponded to fixed models of user behavior, presuming, for example, that the user will view a pre-determined number of items in the search engine results page, or that they have a constant probability of advancing from one item in the result page to the next. Recently, a number of proposals for models of user behavior have emerged that are parameterized in terms of the number of relevant documents (or other material) a user expects to be required to address their information need. That recent work has demonstrated that T, the user’s a priori utility expectation, i..