Accuracy of the parametric model (see Eqs. (3) and (4)) in reproducing P_3D and P_1D measurements from all the TRAINING simulations. Lines and shaded areas show the mean and standard deviation of the relative difference between simulation measurements from the 1650 snapshots of the TRAINING simulations and best-fitting models to these, respectively. The accuracy of the model in recovering P_3D and P_1D is 2.4 and 0.6%, respectively, on scales not strongly affected by cosmic variance.