Table 3

Farm-level predictors used in statistical analyses of associations with between-farm association frequency

Predictor variable

Data type

Description

% missing (n = 662)


Species

Categorical

Production type or poultry species

54.38

Bird count a

Binary (large vs. small)

Total number of birds on site

41.39

House count a

Binary (large vs. small)

Total number of poultry houses on site

40.03

Indoors b

Binary (yes vs. no)

Categorisation of whether the premises houses any of its birds indoors (e.g. barn, cage or pole barn)

38.97

Outdoors b

Binary (yes vs. no)

Categorisation of whether the premises houses any of its birds outside

38.97

Free-range b

Binary (yes vs. no)

Categorisation of whether the premises has registered any free range birds

38.97

Housing other b

Binary (yes vs. no)

Categorisation of whether the premises keeps any of its birds in other housing

38.97

Partial housing b

Binary (yes vs. no)

Categorisation of whether the premises keeps any of its birds in partial housing (e.g. coop, brooder house, shelter pen or grass run)

38.97

Integrated

Binary (yes vs. no)

Whether premises is part of an integrated company or associated with a company

6.95

Region

Categorical (Eastc, Scotland, Wales, Westc vs. Northc)

Regional location of premises within GB based on the county in the premises address

8.61


aFollowing categorisation of original numeric variables

b Original categorisation for variables indicating the farm management type

cGeographical regions of England

Nickbakhsh et al. BMC Veterinary Research 2011 7:66   doi:10.1186/1746-6148-7-66

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