1. A computer-implemented method of evaluating candidate answers to questions in a target knowledge domain, the method comprising: identifying, by a question answering module, a plurality of evidence items in the target knowledge domain; identifying, by the question answering module, a plurality of answers to questions in the target knowledge domain; determining, by the question answering module, associations between each evidence item and one or more of the answers; receiving, by the question answering module, a question; receiving, by the question answering module, values for the one or more evidence items; and providing, by the question answering module, an answer to the question in dependence upon the associations between each evidence item and one or more of the answers and the values for the one or more evidence items.