Table 4.

Mann Whitney U test statistics for climatic variables broken by eastern and western regions. The table shows the Mann Whitney U test statistics for climatic variables in census block groups with and without WNV disease incidence for the year of occurrence broken into eastern and western regions. There were 24, 30, 11, 6, and 11 census block groups with WNV disease in the Eastern region in 2002, 2003, 2004, 2005, and 2006 respectively. There were 29, 99, 12, 29, and 24 census block groups with WNV disease in the Western region in 2002, 2003, 2004, 2005, and 2006 respectively.

Variable	Year/Region	With WNV Mean Rank	Without WNV Mean Rank	z-score	P
Precipitation	2002/East	701	695	-0.16	0.88
	2002/West	776	619	-2.31	0.021
	2003/East	733	694	-0.53	0.6
	2003/West	465	637	-4.57	<0.001
	2004/East	678	695	-0.14	0.89
	2004/West	626	623	-0.23	0.98
	2005/East	679	695	-0.96	0.92
	2005/West	623	624	-0.01	0.99
	2006/East	421	697	-2.27	0.023
	2006/West	526	625	-1.35	0.18
Dewpoint	2002/East	708	695	-0.74	0.94
	2002/West	581	625	-0.65	0.52
	2003/East	747	694	-0.71	0.48
	2003/West	479	636	-4.15	<0.001
	2004/East	516	696	-1.49	0.14
	2004/West	512	625	-1.08	0.28
	2005/East	547	695	-0.91	0.37
	2005/West	616	624	-0.11	0.91
	2006/East	881	694	-1.55	0.12
	2006/West	450	627	-2.4	0.017
Max. Temp.	2002/East	780	694	-1.04	0.3
	2002/West	579	625	-0.67	0.5
	2003/East	730	695	-0.49	0.63
	2003/West	607	636	-0.48	0.64
	2004/East	536	696	-1.32	0.19
	2004/West	412	626	-2.05	0.041
	2005/East	532	696	-1.0	0.32
	2005/West	557	625	-1.01	0.31
	2006/East	877	694	-1.51	0.13
	2006/West	559	625	-0.88	0.38
Min. Temp.	2002/East	741	694	-0.57	0.57
	2002/West	532	626	-1.38	0.17
	2003/East	712	695	-0.234	0.81
	2003/West	483	636	-4.04	<0.001
	2004/East	598	695	-0.80	0.42
	2004/West	397	626	-2.19	0.029
	2005/East	556	696	-0.85	0.40
	2005/West	486	627	-2.08	0.037
	2006/East	820	694	-1.04	0.30
	2006/West	397	628	-3.12	0.002