These maps were created using all years of survey data (2007-2011). They illustrate hot-spots of disease severity. The following two approaches were taken to create the maps:
Map 1. Geo-statistical Hot-spots:The Getis-Ord Gi* statistic was calculated on the survey data based on the disease severity rating. A search distance optimized to the right distance by computing a Multi-distance clustering analysis. The resulting Z score identifies statistically significant hot-spots (Z>2.0, red dots) and cold-spots (Z<-2.0, blue dots).
Map 2. Spatial Interpolation: An interpolated surface based on the disease severity rating was created using Inverse Distance Weighting methodology. The resulting surface is masked to the wheat growing areas