Fig. 2

a Agglomerative hierarchical clustering of model parameters. b Verification of the δ-condition. Recursively, at each level, a pair of most similar clusters is merged into a single cluster and δ-condition is verified. Linkages between clusters, at each stage of clustering, are plotted at high \(\frac {1}{m}{\sum \nolimits }_{i=1}^{m}(1-\rho ^{2})\), where m is the size of a new cluster, compared to a previous linkage. Identifiability results from violation of either of the δ-condition or ζ-condition therefore even parameters that have sensitivities above a threshold can be non-identifiable. Non-identifiable parameters are marked red