  Counterfactual explanations, and their associated algorithmic recourse, are
typically leveraged to understand, explain, and potentially alter a prediction
coming from a black-box classifier. In this paper, we propose to extend the use
of counterfactuals to evaluate progress in sequential decision making tasks. To
this end, we introduce a model-agnostic modular framework, TraCE (Trajectory
Counterfactual Explanation) scores, which is able to distill and condense
progress in highly complex scenarios into a single value. We demonstrate
TraCE's utility across domains by showcasing its main properties in two case
studies spanning healthcare and climate change.
