In the following, we use x 0 = 1 and a = 3 for the reference distribution q(x), such that the barrier height is ax 0 4 = 3 (Figure ). The experimentally measured expectation value of the observables x is set to Y = 0.8. The error is σ = 0.2. We use rejection sampling to generate an ensemble of N = 10000 independent random points for ensemble refinement.