Table 4.

The final generalised linear mixed model presenting risk factors of bovine coronavirus detection in nasal swabs from individual cattle by reverse transcriptase PCR (number of observations = 229)

Variable	Category	Odds ratio (OR)	β (SE)	z	P > |z|	95% CI
Herd size*
	Smaller (≤77)	reference
	Medium (80–590)	4.22	1.92	3.16	0.004	1.73–10.30
	Larger (≥750)	0.02	0.02	-4.24	<0.001	0.002–0.11
Fixed effect		Variance	β (SE)c	95% CI
	Age group	1.06	1.66	0.05–23.16

SE – standard error; z – Wald z statistic; CI – confidence interval; ^* – age group and herd size variables were categorised into three groups by values of ≤25^th, 25^th–75^th and ≥75^th centile prior to analysis