Joint marginal posterior on the branching ratio ξ between low-mass isotropic and Gaussian spin tilt distributions under the SUBPOPULATIONS model, as well as the location (μ_χ, ﹩{\mu }_{\chi }^{\,{\rm{Iso}}\,}﹩, and ﹩{\sigma }_{\chi }^{\,{\rm{High\, Iso}}\,}﹩) and scale (σ_χ, ﹩{\sigma }_{\chi }^{\,{\rm{Iso}}\,}﹩, and ﹩{\sigma }_{\chi }^{\,{\rm{High\, Iso}}\,}﹩) parameters of the spin distributions for each respective subpopulation. Contours shown enclose the 50% and 90% credible regions.