Stellar mass–velocity dispersion plane colour-coded by light-weighted age (left) and light-weighted stellar metallicity (right). For visualisation purposes, the age and metallicity have been LOESS-smoothed. Vectors in the bottom right corner are proportional to the partial correlation coefficients, computed for the original (non-smoothed) physical parameters, following Scholz-Díaz et al. (2022, 2024). The red line marks the direction of maximal increase in age/metallicity. The grey vectors refer to a correlation coefficient of 0.5 for comparison.