Figure 6.34 Icelandic measles diffusion chains: simultaneous equation models. The maps show (A) spread from Keflavíkur to Reykjavíkur, on to Akureyrar, and finally from Akureyrar into the local medical districts of Hofsós and (B) Siglufjarðar. (C) Spread from Keflavíkur to Reykjavíkur across to Ísafjarðar, with local spread (neighbourhood) from thence to Bolungarvíkur. The identifiers, t, t–1 and t–2, reflect the monthly time steps in the causal chains. Arrows run from impulse districts to the response districts. The graphs plot the district monthly reported cases of measles (grey bars) against simultaneous equation estimates of cases (solid black lines) and epidemic probabilities (pecked lines). The model calibration period is 1945–57 and the forecast period is 1958–70.

Source: Adapted from Cliff et al, Measles: An Historical Geography of a Major Human Viral Disease from Global Expansion to Local Retreat, 1840–1990, Figure 14.2 and 15.6, p. 384 and 404, Blackwell, Oxford, UK, Copyright © 1993, by permission of the authors.