Comparison of the cINN and an MCMC method when applied to the toy model. The data in the lower triangle (black) were predicted by the cINN method, and the data in the upper triangle (blue) were generated with an MCMC sampler. The dashed blue lines indicate the boundaries of the prior domain, outside of which the prior probability is zero. The dashed red line indicates the upper limit on y₂ as in Eq. (36). The histograms of the analytical solution are omitted since they overlap with the MCMC data. The light shaded areas in the 2D scatter plots indicate the 68% HDR, and the dark shaded areas are the 89%-HDR.