Table 3.

T-test statistics for climatic variables for year preceding occurrence. The table shows the t-test statistics for climatic variables (from year preceding 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	WNV Occurrence Year	Degrees of Freedom	With WNV Mean	Without WNV Mean	t-value	P
Precipitation	2002	54	887	879	0.56	0.58
	2003	145	693	767	-8.19	<0.001
	2004	23	702	761	-4.27	<0.001
	2005	35	819	848	-2.13	0.041
	2006	35	712	698	0.74	0.464
Dewpoint	2002	54	4.83	4.87	-0.37	0.71
	2003	140	3.97	4.43	-6.01	<0.001
	2004	22	3.04	3.41	-2.22	0.037
	2005	35	4.29	4.61	-2.36	0.024
	2006	35	4.71	4.74	-0.23	0.818
Max. Temp.	2002	54	15.4	15.3	-0.57	0.57
	2003	140	15.7	15.7	0.31	0.76
	2004	22	14.8	15.1	-1.88	0.074
	2005	35	15.1	15.2	-0.68	0.5
	2006	35	15.8	15.8	0.07	0.94
Min. Temp.	2002	54	3.93	4.02	-0.57	0.57
	2003	143	3.32	3.84	-5.48	<0.001
	2004	23	2.58	3.07	-2.47	0.021
	2005	35	3.18	3.68	-2.97	0.005
	2006	35	3.77	4.04	-1.48	0.147