Figure 6.8 Calculating R0A: hypothetical 12-area example. (A) Base map with areas reference coded as a1…a12, and associated space–time data matrix with reported cases for each area given in cells. (B) Matrix rearranged to order leading edges, LE and (C) following or trailing edges, FE. (D) Leading and following edges plotted as a phase-transition diagram with susceptible (S), infected (I) and recovered (R) integrals for areas.