Table 4 |
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|
Six logistic models for farm-level factors associated with Campylobacter in broilers in Iceland (n = 28a) |
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|
Variable |
Automated forward selection |
Automated forward stepwise |
Automated backward selection |
Automated backward stepwise |
Manual backward selection using "manure spread in summer" |
Manual backward selection using "manure spread in winter" |
|
|
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|
Median flock size on farm (divided by 1,000) |
0.10 (0.000)b |
0.10 (0.000) |
0.11 (0.000) |
0.09 (0.001) |
0.13 (0.000) |
0.12 (0.000) |
|
Farm water source |
||||||
|
Non-official |
Ref. |
Ref. |
Ref. |
Ref. |
||
|
Non-official treated |
-0.57 (0.066) |
-0.03 (0.913) |
-0.50 (0.169) |
-0.33 (0.370) |
||
|
Official |
-0.60 (0.051) |
-0.76 (0.009) |
-1.04 (0.004) |
-0.99 (0.005) |
||
|
Official treated |
-0.87 (0.032) |
-1.06 (0.006) |
-1.21 (0.006) |
-1.17 (0.007) |
||
|
Other domestic livestock on farm |
-0.65 (0.026) |
-0.60 (0.028) |
-1.01 (0.004) |
-0.90 (0.004) |
||
|
Other commercial poultry on farm |
0.59 (0.000) |
0.59 (0.000) |
-0.72 (0.063) |
-0.59 (0.097) |
||
|
Number of houses on farm |
0.06 (0.038) |
0.13 (0.008) |
0.11 (0.008) |
|||
|
Manure spread on fields in winter seasonc |
0.54 (0.035) |
1.90 (0.014) |
Not included in model |
0.97 (0.004) |
||
|
Manure spread on fields in summer seasonc |
-1.71 (0.028) |
0.92 (0.025) |
Not included in model |
|||
|
Manure stored on farm at any time of year |
-0.83 (0.029) |
-0.76 (0.025) |
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|
Farm has all-in-all-out policy |
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|
AICd of model |
5.09 |
5.09 |
4.86 |
4.78 |
4.94 |
4.79 |
|
|
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|
a Only farms with complete data for all variables are included b Regression coefficient (p-value). c Variables are highly correlated (τb ≥ 0.8) d Akaike's Information Criterion |
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|
Guerin et al. Acta Veterinaria Scandinavica 2007 49:18 doi:10.1186/1751-0147-49-18 |
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