Distribution in redshift for the Planck cosmological cluster sample. The observed number counts (red), are compared to our best-fit model prediction (blue). The dashed and dot-dashed histograms are the best-fit models from the Planck SZ power spectrum and Planck CMB power spectrum fits, respectively. The cyan long dashed histogram is the best fit CMB and SZ when the bias is free (see Sect. 6.3). The uncertainties on the observed counts, shown for illustration only, are the standard deviation based on the observed counts, except for empty bins where we show the inferred 84% upper limit on the predicted counts assuming a Poissonian distribution. See Sect. 6 for more discussion.