Fig. 2

Correlation between the trend parameter for a county and any other county as a function of distance. a The curve represents the decaying influence that any other county has on a given county as the distance between them increases. Three distances were chosen arbitrarily for demonstration and are shown here as the three colored boxes, and in (b) as circles around a given county. b The high, moderate, and low areas of influence for Orleans Parish, LA, are depicted as circles overlaying the prevalence map. Counties within the small circle had a much greater influence on the regional trend estimate for Orleans Parish than those within the low area