Equilibrium ratios for the experimental databases.

For each of the four experimental databases considered (listed on the first column: Equal Sites, NC, IB, Diff & Coop) the equilibrium dose-response curve was fitted both with the mathematical expression corresponding to an IB description and with that of an NC description (Eqs (1) and (2) in the main text), obtaining K10 and K01, or K and K/ω, respectively. For the experimental databases labeled Equal Sites, NC and IB both fittings are good, because of the indistinguishability reasons. The considered articles fitted the data (dose-response curve in equilibrium) using a two-site model (TS); this model is described in detail in the S1 Text. The TS model provides two parameters, K1 and K2. By comparing the equilibrium dose-response curves from IB and NC models, with that of the TS model, a mathematical relationship between K1-K2 and K10-K01, and K1-K2 and K-K/ω was obtained. Summarizing, the papers provide K1-K2, and using the mentioned relationships the inferred K10-K01 and K-K/ω are calculated from those reported values, to be compared with the inferred K10-K01 and K-K/ω from fitting with IB and NC models. Data coming from Diff and Coop does not have reported K1 nd K2, that is why that row is empty.