Fig. 4

3D surface density plot of the distribution of differences in M-values to differences in Beta-values from E-GEOD-55763 (left) and E-GEOD-68379 (right). The difference in M-values (\(\Delta _{M}\)) is mapped to the corresponding differences in Beta-values (\(\Delta _{Beta}\)) observed in the data set by comparing two groups of five observations each with random group assignment in 5000 simulations . For \(\Delta _{M}\) larger than 7, we run 10000 simulations. The small group size of five was chosen for demonstration purposes and is by no means a sufficient group size