Figure 2.—

Synopsis of the ABC parameter estimation approach. Step 1 usually includes a loop over hundreds of thousands to millions of simulations. It is the most time-consuming task, generally involving several days of computations. In contrast, the computations in steps 2 and 3 usually take seconds or minutes. To validate the ABC approach, steps 2 and 3 can be repeated hundreds of times on pseudo-observed data generated by step 1-type simulations based on fixed predefined parameter values.