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Table 1 Descriptive statistics of major demographic variables of observed and the matched dataset

From: Spread of porcine circovirus associated disease (PCVAD) in Ontario (Canada) swine herds: Part II. Matched case-control study

 

Control times

Case times

Variable

Mean

Median

sd*

iqr*

N*

Mean

Median

sd*

iqr*

N*

Herd PRRSv status (proportion positive)

0.86

1.00

0.35

0.00

510

0.91

1.00

0.29

0.00

170

Cumulative local exposure (proportion)

0.16

 

0.37

 

510

0.17

 

0.38

 

170

Number of high-risk exposures

0.04

0.00

0.20

0.00

510

0.08

0.00

0.30

0.00

170

High-risk local exposure (proportion)

0.04

 

0.19

 

510

0.08

 

0.27

 

170

Number of nursery contacts/month

1.09

0.00

2.41

0.50

510

0.75

0.00

2.09

0.00

170

Number of feed contacts/month

4.06

4.00

2.53

2.33

510

4.59

4.00

3.73

4.00

170

Number of direct contactsa/month

1.39

0.00

2.46

2.00

510

1.13

0.00

2.20

1.17

170

Number of indirect contactsb/month

6.61

5.67

4.25

3.67

510

7.01

6.00

4.08

4.00

170

Total capacity for growing animals

2161.33

2000.00

1586.11

1525.00

510

2180.14

2000.00

1461.31

1520.00

170

Easting (100 kms)

4.87

4.87

0.57

0.65

510

5.05

5.01

0.71

0.50

170

Number of sows

321.60

240.00

281.66

280.00

279

357.13

240.00

398.05

290.00

92

Number of nursery pigs

1363.81

1000.00

1170.90

1600.00

396

1355.88

900.00

1400.92

1600.00

116

Number of finisher pigs

1308.81

1100.00

1083.18

361.00

510

1421.15

1250.00

982.14

1350.00

127

Number of breeding contacts/month

5.11

4.08

4.27

6.92

278

5.57

4.67

4.36

7.38

92

Herd type: farrow-to-finish

43.14

   

220

41.18

   

70

Herd type: farrow-to-grow

11.37

   

58

12.94

   

22

Herd type: finisher

21.76

   

111

30.00

   

51

Herd type: nursery

17.84

   

91

12.35

   

21

Herd type: nursery and finisher

5.88

   

30

3.53

   

6

High risk exposure: not present

96.27

   

491

92.35

   

157

High risk exposure: within ownership

0.00

   

0

2.94

   

5

High risk exposure: outside ownership

3.73

   

19

4.71

   

8

  1. *sd = standard deviation, iqr = interquartile range, N = number of observations
  2. a frequency of monthly contacts through incoming movement of nursery and finisher pigs
  3. b frequency of monthly contacts through incoming visits of service vehicles without pigs (feed deliveries, veterinarians, veterinary suppliers, other service personnel)