Table 2.

Median, minimum, and maximum survival time in the clear and IR only cohorts, and by each explanatory variable.

Variable	Level	Survival time (years)
		Median	Min	Max
First WHT status in 2012	Clear	4.21	0.02	5.46
	IR	2.07	0.02	5.09
Season in which 2012 WHT took place	Spring	4.63	0.02	4.84
	Summer	4.36	0.05	5.46
	Autumn	4.11	0.02	5.28
	Winter	4.08	0.02	5.08
Number of incidents in the previous 10 years	0–2	4.22	0.02	5.46
	3 or more	2.36	0.02	5.42
Geographical risk area	England high-risk	4.07	0.02	5.28
	England Edge	4.26	0.05	5.46
	Wales	4.31	0.12	5.19
Annual rolling county level incidence at end of 2012	0–14.6 per 100 herd years at risk	4.27	0.04	5.46
	>14.6 per 100 herd years at risk	4.31	0.12	5.19
Herd type	Beef	4.23	0.02	5.46
	Dairy	3.76	0.02	5.22
	Other	4.25	0.18	4.99
Herd size	0–10	4.34	0.03	5.25
	11–50	4.36	0.05	5.42
	51–100	4.25	0.06	5.46
	101–200	4.11	0.02	5.22
	201–300	3.40	0.02	5.15
	>300	2.57	0.02	5.24