Figure 4

Absolute t-values for landscape variables based on Students t-test. This graphic represents the absolute t-value from the Students t-test comparing the means of landscape variables for census block groups with and without human WNV disease incidence. Those landscape variables to the left of the vertical line are ones in which there were lower means for census block groups with WNV disease incidence (negative) and those to the right were ones in which there were higher means for census block groups with WNV disease incidence (positive). All except grassland, water, and slope were significant (P <= 0.006). Those labelled with * used the 'equal variance not assumed' version of the t-test in SPSS. The agriculture class was reclassified from alfalfa, corn, soybeans, and other row crops.