One-to-one comparison of the true and model-predicted mass fractions of decomposed structures. From left to right, the panels display mass fractions for Au-18, Au-23, and Au-28. The black, red, blue, and green markers denote the bar, bulge, disc, and stellar halo components, respectively. The triangles, squares, pentagons, and circles indicate mock datasets with viewing angles (θ_T, φ_T) = (85° ,50° ), (85° ,80° ), (89° ,50° ), and (89° ,80° ), respectively. The coloured error bars in each panel represent the uncertainties for different components. The dashed lines represent the equality of model-predicted fractions f_true and true fractions f_model, while the dotted lines are ±0.1 away from the dashed lines.