Probability density of chirp mass and redshift in the (ℳ − z) space for the three sets of parameters for Pop III binaries. Top: actual parameters of the sources in the mock population, ℳ_s, mock and z_s, mock. Middle: actual parameters of the binaries that were detected, ℳ_s, det and z_s, det. Bottom: estimated medians of the parameters for each of the detected compact binaries, ℳ_med, det and z_med, det. The blue contour encloses the region of 90% probability.