Figure 7

Infection risk versus average polarity. A Herds with an average in-strength of less than 4 (n = 8478); B Herds with an average in-strength of 4 or more (n = 4875). Polarity is an indicator of the trading behaviour of a herd, where herds with a polarity between −1 and −0.25 can be considered as predominantly selling herds, between −0.25 and 0.25 as neither predominantly buying or selling herds, and between 0.25 and 1 as predominantly buying herds. Points are coloured according to the probability of a herd being infected. Lines show the density curve. For the definition of infection risk posed see text.