2D and 1D histograms of the RE from linear interpolation and chi squared fitting of M_BH on the test set for NGC 7582. On the left, we plotted the RE when estimating the M_BH of the test set as 2D histograms. On the right, we plotted the same RE but as a 1D histogram. On top, we plotted the RE from the linear interpolation and at the bottom, we plotted the RE from the chi squared fitting. The y-axis represents the RE values. The x-axis of the 2D histograms is in $log(\frac{M_{\mathrm{BH}}}{M_{\odot }})$ and the 1D histograms axis is in number of estimations.