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Table 4 Univariable negative binomial models using GEE1 approach

From: Factors associated with whole carcass condemnation rates in provincially-inspected abattoirs in Ontario 2001-2007: implications for food animal syndromic surveillance

Covariate IRR2 Robust Standard Error P-value 95% CI
Animal class     
Calves --- --- --- ---
Cows 4.83 1.35 < 0.001 2.80 - 8.34
Heifers 0.43 0.09 < 0.001 0.28 - 0.64
Steers 0.51 0.11 0.01 0.34 - 0.77
Year     
2001 --- --- --- ---
2002 1.02 0.14 0.90 0.77 - 1.34
2003 0.90 0.14 0.49 0.67 - 1.22
2004 0.70 0.15 0.10 0.46 - 1.06
2005 0.69 0.14 0.07 0.47 - 1.03
2006 0.75 0.16 0.17 0.50 - 1.13
2007 0.73 0.17 0.18 0.46 - 1.16
Season     
Winter --- --- --- ---
Spring 0.94 0.05 0.20 0.85 - 1.03
Summer 0.86 0.06 0.02 0.76 - 0.98
Fall 0.76 0.07 0.01 0.64 - 0.91
3Audit rating     
C --- --- --- ---
AAA 0.71 0.53 0.64 0.16 - 3.07
AA 0.90 0.37 0.80 0.40 - 2.01
A 1.19 0.48 0.67 0.54 - 2.61
B 1.01 0.42 0.98 0.45 - 2.28
unrated 2.69 1.09 0.01 1.22 - 5.94
# weeks open     
1 - 43 --- --- --- ---
44 - 49 0.72 0.15 0.10 0.48 - 1.08
50 - 51 0.71 0.16 0.13 0.46 - 1.11
52 0.92 0.29 0.78 0.49 - 1.70
# animal processed     
1 - 286 --- --- --- ---
287 - 498 1.01 0.15 0.95 0.75 - 1.35
499 - 841 1.14 0.19 0.44 0.82 - 1.58
842 - 27286 1.29 0.42 0.43 0.68 - 2.46
Region     
Central --- --- --- ---
Eastern 9.88 6.83 0.01 2.55 - 38.26
Northern 3.78 2.49 0.04 1.04 - 13.74
Southern 7.91 6.56 0.01 1.56 - 40.21
Western 1.60 2.31 0.75 0.09 - 27.23
Price     
Below median --- --- --- ---
Above median 1.11 0.06 0.04 1.00 - 1.23
  1. 1 Generalized estimating equation using an exchangeable correlation structure to accommodate repeated measurements among provincial abattoirs
  2. 2 Incidence rate ratio
  3. 3 Model would not converge therefore results represent univariable negative binomial model
  4. Univariable negative binomial models using a GEE1 approach modeling the association between condemnation rates in Ontario provincial abattoirs and animal class, year, season, audit rating, the number of weeks an abattoir was open each year, the number of cattle an abattoir processed each year, census agricultural region and median yearly sales-price for animal class.