Table 2

Crude odds ratios before and after removal of records with missing data: scenario 2 analyses

Full data (n = 662 farms)

Following the removal of records (n = 348 farms)


Farm-level predictors

ORa

s.e. ORb

p-value

ORa

s.e. ORb

p-value

% change


L vs. S bird countd

7.304

1.485

<0.0001

5.588

1.369

<0.0001

23.5

L vs. S house countd

1.783

1.289

0.023

1.879

1.310

0.019

5.1

Indoors

2.888

1.425

0.003

3.822

1.472

0.001

24.4

Free-range

0.280

1.529

0.003

0.227

1.579

0.001

18.9

Housing other

0.363

1.648

0.043

0.338

1.656

0.031

6.9

Partial housing

0.890

1.991

0.866

0.592

2.254

0.518

33.5c

Integrated

0.544

1.232

0.003

0.554

1.319

0.033

1.8

East

0.446

1.401

0.017

0.426

1.538

0.047

4.5

Scotland

0.061

2.837

0.007

0.090

2.914

0.024

32.2c

Wales

0.090

1.722

<0.0001

0.116

2.176

0.006

22.4

West

0.047

1.477

<0.0001

0.056

1.583

<0.0001

16.1


aOR = odds ratio; bs.e. = standard error of the odds ratio; c >25% change in odds ratio but direction of association and significance is comparable; dL = large, S = small.

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

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