Constraints on hyperparameters of the two-population mixture model from the analysis of type Ia supernovae in the Hubble flow from the Pantheon+ compilation. The red and blue colours respectively denote the old and young populations (associated with the low- and high-stretch peak of the stretch distribution, respectively). The contours show 1σ and 2σ credible regions containing 68 and 95 per cent of 2D marginalised probability distributions.