Table 1.

Potential risk factors for scrapie considered in the analyses

Attribute	Description, coding and comments
region	Great Britain divided into the 13 regions indicated in figure 1
farm type	hill (H); upland (U); lowland (L)
flock type	purebred (P); commercial (C); both (PC)
flock size	log(number of rams and ewes over one year old)
stocking density	quartiles for stocking density (number of rams and ewes over one year old divided by the number of acres grazed): <0.85 (Q1); <1.56 (Q2); <2.51 (Q3); >2.51 (Q4)
proportion homebred	the proportion of rams and ewes over one year old born on the farm; the AOR gives the change in odds for an increase of 10% in the proportion of homebred animals
rams bought-in	did (1) or did not (0) purchase rams in the previous 12 months
ewes bought-in	did (1) or did not (0) purchase ewes in the previous 12 months
lambs bought-in	did (1) or did not (0) purchase lambs in the previous 12 months
sheep temporarily moved elsewhere	sheep did (1) or did not (0) temporarily spend time on other farms in the last 12 months (e.g. over-wintering, summer grazing, fattening)
lambing practices	sheep lambed: in individual pens in a building (1); unconfined at pasture (2); in group pens at pasture (3); in group pens in a building (4); did not lamb in the previous 12 months (5)
lambing location	sheep lambed: always in the same location (1); sometimes in the same location (2); never in the same location (3)
breeds kept on farm	most popular breeds and crossbreeds of ewes and rams (those reported on over 150 farms); coded as do (1) or do not (0) keep breed on the farm