  In this work, we present a novel way of computing IPS using a position-bias
model for deterministic logging policies. This technique significantly widens
the policies on which OPE can be used. We validate this technique using two
different experiments on industry-scale data. The OPE results are clearly
strongly correlated with the online results, with some constant bias. The
estimator requires the examination model to be a reasonably accurate
approximation of real user behaviour.

Information Retrieval;Machine Learning