The number of cows predicted to test false positive in an average (117-cow) herd.

<p>Probability densities drawn for SICCT and γIFN with the probability of individual cows testing positive (Pc) equalling 1-<i>Sp</i>. The red probability density gives the animals based on the average values of <i>Sp</i> taken from the literature (95% confidence-limit densities also given), the purple density is based on the DEFRA-published <i>Sp</i> estimate (standard interpretation for SICCT).