Figure 1. (A) The 250 best fitting curves for the surveillance data points shown in black from a sample of 25 000 randomly generated combinations of the parameters r, f0, t0 and φ in the UNAIDS Reference Group model. (B) Of the original sample of 25 000 curves, the 20 shown include the best-fitting curve (defined by the maximum likelihood) and those that are statistically indistinguishable from the best fit. This example illustrates how multiple combinations of the Reference Group model parameters may fit a given data set with approximately equal validity.
