Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA

Table 3 Random forest spatial model results.

Variables Tested and Model Type	Year	R²	Most important variables in model
All variables Random Forest	All		Precip W33, W19, W28
			Temp W27
		76.89	Pct Black
	2004	81.77	Precip W23, W29, W33
	2005		Precip W28, W21
		64.48	Temp W33
	2006	74.76	Precip W29, W18, W19, W33
	2007		Precip W15, W28
		62.88	Temp W17
Weather variables only Random Forest	All		Precip W33, W19
		78.77	Temp W27
	2004	82.99	Precip W33, W23, W29
	2005	70.55	Precip W32, W28, W19
	2006	77.03	Precip W33, W29, W19
	2007		Precip W15, W21
		67.01	Temp W17
Non-weather variables only. Random Forest	All	13.27	Pct Black, Human population, Elevation range
	2004	47.34	Pct Black, Maximum elevation, Minimum elevation
	2005	34.47	% pre-40's housing, Pct Black, % 50's housing
	2006	42.27	Pct Black, maximum elevation, % 90's housing
	2007	37.95	Pct Black, maximum elevation, mean elevation

The R² value indicates the ability of random forests to predict mosquito infection in weeks 32 to 34. Also included are the most important variables from the models listed in order of importance. Results are divided according to which variables were included in the models. See Additional File 3: Spatial, for a regression tree graphic.

ISSN: 1756-3305