Relation between the latent variable f(η) = w₀ + ∑_jw_jη_j calculated for each simulated cluster in the test sample after performing logistic regression with 35 surface brightness features, and the values of ℒ_det and ℒ_ext as provided by eSASS for those matched to a detection. Each dot stands for a simulated cluster, density contours ease visualisation in crowded regions. Undetected clusters have no associated ℒ_det value (red histogram in the lower panel). Clusters detected but not categorised as extended have zero value for ℒ_ext (orange histogram). The apparent correlation between f and both measurements indicate that the model has “discovered” the importance of ℒ_det and ℒ_ext in the selection process.