Optimizing Provider Recruitment for Influenza Surveillance Networks
Figure 4
Location and population coverage of optimized ILINets.
(a) Shading indicates zip code level population sizes, as reported in the 2000 census. Circles indicate the location (zip code) of the first ten providers selected when Google Flu Trends is included as a provider (green) and when it is not (pink). Numbers indicate selection order, with zero being the first provider selected and nine the tenth provider selected. (b) The cumulative population densities covered increase as each ILINet grows. Cumulative density is estimated by dividing total population of all provider zip codes by total area of all provider zip codes. While ILINets designed using the geographic (orange) and random (green) methods primarily target zip codes with high population densities, submodular optimization (purple) targets zip codes that provide maximal information, regardless of population density. All three networks cover approximately the same total number of people.