Table 2. Parameter estimates and standard errors (SE) for the interaction of Jamestown Canyon virus serostatus and environmental covariates describing suburban forest preserves in Cook County, Illinois (1996–1999).

Significant (α = 0.15) interaction terms identify variation in selection of the environmental covariate by serostatus (seronegative or seropositive for Jamestown Canyon virus).

Effect	Main effect	P	Condition effect	P	Interaction effect	P
BOUND * COND	0.17 (0.07)	< .001	0.52 (0.08)	< .001	0.26 (0.08)	< .001
STAG * COND	0.10 (0.06)	0.01	0.54 (0.08)	< .001	0.000 (0.08)	0.99
RIVER * COND	0.26 (0.06)	< .001	0.54 (0.08)	< .001	0.04 (0.08)	0.60
EDGE * COND	0.40 (0.06)	< .001	0.57 (0.09)	< .001	-0.09 (0.08)	0.26
ROAD * COND	0.10 (0.06)	0.01	0.54 (0.08)	< .001	0.02 (0.08)	0.77
POP * COND	-0.52 (0.07)	< .001	0.56 (0.09)	< .001	0.64 (0.09)	< .001
PRECIP t * COND	-0.26 (0.14)	0.06	0.54 (0.08)	< .001	0.20 (0.09)	0.02
PRECIP t-1 * COND	0.77 (0.21)	< .001	0.50 (0.09)	< .001	0.13 (0.09)	0.15

BOUND is distance forest preserve boundary, COND is Jamestown Canyon virus serostatus of deer (0 = seronegative, 1 = seropositive), STAG is proportion of wetlands in each grid cell, RIVER is distance to nearest river, EDGE is length of edge habitat in each grid cell, ROAD is length of road in each grid cell, POP is distance to nearest populated place, PRECIP is total precipitation level in year t or t-1.