Metamorphic testing (MT) is proposed to alleviate oracle problem in software testing

which verifies software under testing (SUT) by checking whether inputs and outputs satisfy metamorphic relation (MR).MR

the constraint constructed from the propriety of SUT

plays a key role in MT and becomes focus in MT researching.Failure detecting ratio (FDR) is a popular measure for failure detecting ability of MR.However

FDR is the mean of failure detecting ratios of a MR applied on different mutants.This averaging covers some important properties of MR.In this paper

sensitivity of MR is defined

which is a multi-dimension information vector consisted of failure detecting ratios on all mutants.Sensitivity of MR reflects more fully characteristics of MR than FDR and allows more possibility in MT researching.One typical application of sensitivity of MR is the cluster analysis on MR set

in order to find some clues of the underlying relevant between the requirement of MR and its failure detecting ability.K-means algorithm

a classical cluster analysis algorithm

based on MR sensitivity is applied in the experiment.The experiment results show that the sensitivity of MR supports cluster analysis strongly and the analysis offers some useful knowledge.Sensitivity of MR will be a good method and essential rationale for MT researching.