X-ray luminosity (L_X) vs. richness (λ) for clusters with λ ≥ 20. Clusters with substructure are marked with black circles, and clusters without as red circles. The solid black (solid cyan) line represents the best-fit scaling relation for clusters with (without) substructure. The dashed blue line shows the relation fitted to the full sample (λ ≥ 20). All fits were obtained using the LINMIX Bayesian regression method, which accounts for measurement errors in both variables.