with respect to p(x). The Jayne's measure 26 m(x) guarantees invariance of information under variable transformation. Although it cancels in the expression above, m(x) is needed to define a proper difference between the information of the two ensembles. As we shall see below, this difference becomes a difference in energies for Boltzmann distributions, as has been established previously. Let us assume that probability distributions are given by Boltzmann distributions. For a potential energy surface U q (x) defining the reference ensemble, we then have