Table 1.

Farm-level categorical variables available for analysis of Campylobacter colonization of broilers in Iceland (n = 28^a)

Variable	Description of variable	Number of farms
Manure spread on fields in summer seasonb	Yes	11
	No	17
Manure spread on fields in winter seasonb	Yes	9
	No	19
Manure stored on farm at any time of year	Yes	10
	No	18
Other domestic livestock on farm	Yes	9
	No	19
Other commercial poultry on farm	Yes	10
	No	18
Farm has all-in-all-out policy	Yes	18
	No	10
Farm water source	Non-official	17
	Non-official treated	4
	Official	4
	Official treated	3

^a Only farms with complete data for all variables are included

^b Variables are highly correlated (τ_b ≥ 0.8)