Posterior predictive flux for a spectrum with noise σ = 0.03. The posterior predicted flux (orange line) is computed from the ensemble mean optical depth field in redshift space. The blue shaded region indicates the 1-σ region, corresponding to the standard deviation of the noise in this line of sight. This test checks whether the data model can accurately account for the observations. Any significant mismatch would immediately indicate a breakdown of the applicability of the data model or error of the inference framework. Our method recovers the transmitted flux fraction correctly within the noise uncertainty.