Table 6.

The best-fit Accelerated Failure Time (AFT) model for the clinical infectious phase duration (threshold-defined and non-threshold defined approaches) in cattle (Weibull distribution shape parameter = 4.08 for threshold and 3.46 for non-threshold), n is the number of animals in each category.

Variables	Category	n	Coefficient (β)	95% Cl	Time ratio	p-value
MODEL FOR THRESHOLD APPROACH
	Intercept		2.22	2.1–2.3		<0.0001
Serotype	O	22	−0.09	−0.25 to 0.08	0.9	0.3302
	Asia1	12	0.02	−0.25 to 0.29	1.0	0.9096
	A	55	0
Exposure method 3	CTC	8	−0.4	−0.7 to −0.09	0.7	0.0112
	PTC	29	0.006	−0.17 to 0.18	1.0	0.9508
	IDL	6	0.06	−0.24 to 0.35	1.1	0.7115
	SN	46	0
MODEL FOR NON-THRESHOLD APPROACH
	Intercept		2.46	2.33 to 2.57		<0.0001
Serotype	O	22	−0.08	−0.31 to 0.16	0.9	0.5207
	Asia1	12	−0.06	−0.44 to 0.31	0.9	0.7397
	A	55	0
Exposure method 3	CTC	8	−0.52	−0.90 to −0.15	0.6	0.0065
	PTC	29	−0.03	−0.26 to 0.21	1.0	0.8282
	IDL	6	0.22	−0.38 to 0.81	1.2	0.4778
	SN	46	0