Histogram of the best-fitting slope α distribution, obtained fitting a power-law mass function to a sample of mock clumps extracted either from a power-law function (first two panels) or a Schechter function (last two panels). The plots to the left refer to cases in which the fitted sample was large (∼1000 objects), while for those to the right the sample was small (∼100 objects). When present (because within the interval of explored values), the red line marks the input slope assumed for both the power-law and the Schechter mock distributions (α = 2). The values in the legend of each histogram are the median of each distribution for the corresponding parameter, with uncertainties given by the 84th percentile minus the median and the median minus the 16th percentile (upper and lower uncertainty, respectively). The same values are also reported as black dashed vertical lines in the histograms.