Richness-mass scaling. The solid line marks the mean fitted regression line of log(n200) on lgM200, while the dashed lines show this mean plus or minus the intrinsic scatter σ_scat. The shaded region marks the 68% highest posterior interval for the regression. Error bars on the data points represent observed errors for both variables. The distances between the data and the regression line is due in part to the measurement error and in part to the intrinsic scatter.