Marginalised chi-squares χ_norm² = (χ² − χ_min²)/Δχ_CL² as a function of model-recovered bar pattern speeds Ω_p for bar end-on cases (φ_T ≤ 30°). Left panel: the results from the original models. Right panel: the results from the revised models with stronger assumptions that the bars are strong (p_bar ≤ 0.50). Each fold line represents a complete set of modelling runs. The red, blue, magenta, black fold lines denote the viewing angles of the mock data sets (θ_T, φ_T) = (85° ,10° ), (85° ,30° ), (89° ,10° ), and (89° ,30° ), respectively. The horizontal dashed lines represent 1σ (68%, χ_norm² = 1) and 2σ (95%, χ_norm² = 2) confidence levels, and the vertical dotted lines denote the true bar pattern speed of Au-23, with its value shown by the green annotations. The coloured annotations outside each panel represent the values of bar axis ratio p_bar in the models.