Before revision: Trace alignment , a procedure for finding common activities and deviations in process executions, does not have a well-established framework for evaluation. A common alignment evaluation tool-reference - based methods - is not applicable if a reference alignment, or ground truth, is not available. On the other hand, reference -free evaluation methods currently are not able to adequately and comprehensively assess  alignment quality.
After revision: Trace alignment algorithms have been used in process mining for discovering the consensus treatment procedures and process deviations. Different alignment algorithms, however, may produce very different results. No widely-adopted method exists for evaluating the results of trace alignment. Existing reference-free evaluation methods cannot adequately and comprehensively assess alignment quality.