Marginal posteriors obtained for the model parameters of magnetogram number 10 of AR 10268 (see Fig. 1b). Colors correspond to the four different chains (indicated in the inset of panel a) having 2000 samples each. The panels correspond to the parameters: (a) a, (b) B₀, (c) R, (d) d₀, (e) ϕ, (f) N_t, (g) x_c, and (h) y_c. The value is written at the bottom left of each panel. is the normalized rank factor used to quantify the convergence between different MC Markov chains to a single distribution. tends to unity when convergence is achieved.