Figure 4. Performance of whole country model versus combination of zonal models. A. Receiver operator curve. Black line, single model for all Colombia (area under the curve [AUC] = 72.4%); gray line, combination of zonal models (AUC = 84.4%). Diagonal line indicates success expected on the basis of chance (AUC = 50%). B. κ value, representing skill at discriminating positive and negative municipalities, above the level expected on the basis of chance. Black line, single model for all Colombia; gray line, combination of zonal models. The probability threshold is the value on the continuous scale of predicted probability of transmission that is used as the cut-off for conversion into a categorical prediction of presence versus absence.