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Table 8 Variables considered for inclusion in two regression models in the cohort study of post-weaning diarrhea

From: Post-weaning diarrhea in pigs weaned without medicinal zinc: risk factors, pathogen dynamics, and association to growth rate

Variables Scale of measurement Model 1 (Cox PH) Model 2 (Mixed linear)
Producer Dichotomous (A, B) Covariate Fixed effect
Pen in nursery Nominal (n = 8) Covariate Fixed effect
Sow/pen before weaning Nominal (n = 45)   Random effect
Dam Nominal (n = 30) Shared frailty Random effect
Dam parity Discrete (1–7) Covariate Fixed effect
Total (still + live born) litter size, dam Discrete (total n pigs 14–28) Covariate Fixed effect
Proportion of litter stillborn Proportion (0–1) Covariate Fixed effect
Sex at insertion to nursery Nominal (castrated male, intact male, female) Covariate Fixed effect
Weight at birth Continuous (grams) Covariate Fixed effect
Weight at birth, dichotomized Dichotomous (low birth weight, normal or high birth weight) Covariate  
Moved in the farrowing unit Dichotomous (stayed with dam, moved) Covariate Fixed effect
Time of weaning Dichotomous (weaned in the farrowing unit, weaned at insertion to nursery)
A Time varying effect was added
Covariate Fixed effect
Weight at insertion Continuous (grams) Covariate Fixed effect
Body condition score at insertion to nursery Dichotomous (normal, below normal) Covariate Fixed effect
Days with hollow flanks Discrete (n days with hollow flanks 0–14)   Fixed effect
Days suffering from diarrhea Nominal: (0 days, 1 day, 2 days, 3 days, 4–6 days)   Fixed effect
  1. Variables considered for inclusion in two regression models investigating risk factors for porcine post-weaning diarrhea (Model 1, Cox proportional hazards model), and factors associated with altered growth rate the first 14 days after insertion to the nursery unit (Model 2, mixed linear regression model)