Sample A: Cover Page of Thesis, Project, or Dissertation Proposal

Sensitivity is defined as the proportion of true positives correctly predicted (e.g., the
percentage of locations where mosquito presence is correctly predicted), whereas specificity
is the proportion of true negatives correctly predicted (e.g., the percentage of locations where
mosquito absence is correctly predicted) (Fielding and Bell 1997, Phillips et al. 2006, Phillips
and Dudik 2008). A model with perfect discrimination between presence and absence will
have an AUC of 1.0. As a general rule, an AUC between 0.5 and 0.7 indicates a poor
discriminative capacity; 0.7-0.9 indicates a reasonable capacity; and > 0.9 indicates a very
good capacity (Brooker et al. 2001, Phillips et al. 2006, Phillips and Dudik 2008). The
distribution map resulting from the “best model” (highest AUC) represents the best
approximation of the species‟ realized niche, as a function of the given environmental
variables of the study area. This map was subsequently exported to ArcGIS 9.2 for use in the
development of a Virginia RVF risk map.
3.7 VIRGINIA RIFT VALLEY FEVER RISK MAP DEVELOPMENT
A weighted suitability model was developed using the ArcGIS Spatial Analyst
extension to create risk maps that visually represent the variation in risk of RVF virus
establishment across Virginia and risk of RVF transmission to humans in Virginia. RVF
virus establishment and transmission to humans is likely to occur where competent mosquito
vectors are present near host populations. Therefore, the model included the MaxEnt
Mosquito Habitat Suitability model as the layer representing competent vector mosquito
distribution in Virginia and three layers representing competent host (domestic animal,
wildlife, and human) density in Virginia. The domestic animal layer, created using the Map
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