Univariable analysis of the association between directed wind speed covariates (time-changing and time-lagged) and time to infection of premises in the largest cluster (n = 3153), northwest of Sydney, during the 2007 equine influenza outbreak in Australia.

aMaximum daily wind speed (‘directed’) based on wind only from within 45° arcs centred on the direction of the k nearest infected premises for k = 1,2,3 (see Figure 2 for details) assuming that premises were infectious for 14 days and one of the nearest k infective premises was the source of infection.
bP-values derived from likelihood ratio tests (LRT) comparing univariable to null Cox regression models.