H₀ and Ω_m constraints from our models in flat ΛCDM cosmology, for the IDEAL (left) and FIDUCIAL (right) datasets with statistical uncertainties of δv_stat = 2.5%. We adopted uniform priors on H₀ of [50, 120] km s⁻¹ Mpc⁻¹ and Ω_m of [0.05, 0.5]. The green shaded regions show the 1σ, 2σ, and 3σ confidence regions based on the constraint on D_Δt only, i.e. P(D_Δt) after marginalising over other mass model parameters, including D_d. The red shaded regions show the corresponding constraints based on P(D_d), after marginalising over D_Δt. The grey histogram shows the constraints based on P(D_d, D_Δt); we have omitted the 2D contours for ease of viewing. Different tilts in the H₀–Ω_m space, when marginalised over D_d and D_Δt, respectively, can break some of the degeneracies, also leading to improved constraints on Ω_m.