Empirical distributions (in blue) of the source-frame mass samples drawn from various mass distributions. The analytical expressions of the distributions are plotted in orange dashed curves. Top-left: Truncated power-law model. Top-right: broken-power law model with smoothing at the lower end of the distribution. Bottom-left: a power-law+Gaussian peak model with smoothing at the lower end of the distribution. Bottom-right: a multi-peak model with smoothing at the lower end of the distribution.