Table 2 T-test statistics for climatic variables for year of occurrence. The table shows the t-test statistics for climatic variables (in year of WNV disease occurrence) in census blocks with and without WNV disease incidence. All of the t-tests used 'equal variance not assumed' version of test in SPSS.
Variable | Year | Degrees of Freedom | With WNV Mean | Without WNV Mean | t-value | P |
|---|---|---|---|---|---|---|
Precipitation | 2002 | 54 | 768 | 763 | -0.33 | 0.74 |
| Â | 2003 | 140 | 719 | 762 | -5.63 | <0.001 |
| Â | 2004 | 22 | 848 | 850 | 0.12 | 0.901 |
| Â | 2005 | 35 | 709 | 698 | 0.66 | 0.515 |
| Â | 2006 | 35 | 743 | 779 | -2.9 | 0.006 |
Dewpoint | 2002 | 54 | 4.35 | 4.4 | 0.50 | 0.62 |
| Â | 2003 | 140 | 3.16 | 3.42 | -3.38 | <0.001 |
| Â | 2004 | 22 | 4.61 | 4.33 | -1.71 | 0.1 |
| Â | 2005 | 35 | 4.73 | 4.74 | -0.10 | 0.922 |
| Â | 2006 | 35 | 4.86 | 5.01 | -1.09 | 0.283 |
Max. Temp. | 2002 | 54 | 15.7 | 15.7 | -0.37 | 0.71 |
| Â | 2003 | 140 | 15.2 | 15.1 | 0.70 | 0.483 |
| Â | 2004 | 22 | 15.2 | 14.8 | -1.86 | 0.076 |
| Â | 2005 | 35 | 15.7 | 15.8 | -0.55 | 0.583 |
| Â | 2006 | 35 | 16.2 | 16.1 | 0.28 | 0.783 |
Min. Temp. | 2002 | 54 | 3.71 | 3.82 | 0.66 | 0.52 |
| Â | 2003 | 143 | 2.73 | 3.09 | -3.75 | <0.001 |
| Â | 2004 | 23 | 3.17 | 3.68 | -2.51 | 0.02 |
| Â | 2005 | 35 | 3.65 | 4.04 | -2.74 | 0.01 |
| Â | 2006 | 35 | 4.29 | 4.55 | -1.56 | 0.128 |