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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.

From: Landscape, demographic, entomological, and climatic associations with human disease incidence of West Nile virus in the state of Iowa, USA

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