Ranks of the true Ω_m (left) and σ₈ (right) in the 1D marginalized posteriors. We have tested 500 different compressions y₀, leading to the distributions represented in the blue histograms. If the posteriors are unbiased and with the proper width, the observed distribution should be pproximately flat (dashed black line). This is the case for σ₈. However, Ω_m exhibits a negative slope that indicate a bias, but still an appropriate posterior size (no apparent curvature).