A method for diagnosing a degree of interference between a plurality of faults in a system under test, the faults being detected by means of applying a test suite to the system under test, includes: 1) for each of the plurality of faults, and for each of a plurality of test syndromes, where a test syndrome is a pattern of passing and failing tests of the test suite, determining relative frequencies at which particular ones of the faults are coupled with particular ones of the syndromes; and 2) using the relative frequencies at which particular ones of the faults are coupled with particular ones of the syndromes to calculate and display to a user, via a graphical user interface, and for the test suite as a whole, test suite degrees of interference between pairs of the faults. Other embodiments are also disclosed.