  Given all this agreement it should not be surprising that PR(H, E), OR(H, E) and PD(H, E), have all been proposed as measures of the degree of incremental support that E provides for  H.[11]  While OD(H, E) has not been suggested for this purpose, we will consider it for reasons of symmetry.  Some authors maintain that one or another of these functions is the unique correct measure of incremental evidence; others think it best to use a variety of measures that capture different evidential relationships.  While this is not the place to adjudicate these issues, we can look to Bayes' Theorem for help in understanding what the various functions measure and in characterizing the formal relationships among them.