Relation between fractal dimension and the observed total cluster mass in Pang catalog clusters (left panels) and Hunt catalog clusters (right panels) in the solar neighborhood for the all-member regions (a and d), for r ≤ r_t (b and e), and for r > r_t (c and f). The quantity s is Spearman’s rank correlation coefficient, and p is the probability of the null hypothesis in the correlation test. A p-value less than 0.05 means rejection of the null hypothesis.