Coupling factor computed using the method outlined in Sect. 2 (q_observed) vs. the coupling factor for each frequency computedusing Eqs. (9)–(11) (q_computed). For visual purposes we show the individual points with uncertainties for the RGB models, and a rectangle for the CHeB models that comprises the results including the uncertainties for that particular model; the horizontal width of each rectangular box indicates the spread in q computed through Eqs. (9)–(11) for all frequencies in a range of five times Δ ν centred around ν_max. The legends show the colour with which each model is indicated.