Predictions of meningitis outbreaks in Niger and Burkina Faso. Observed (yellow) MCM annual log-incidence time series and cross-validated forecast (red) for Niger (A) and Burkina Faso (B) from 1968 to 2005. The grey lines represent each individual forecast produced during the cross-validation process. The values in the green area correspond to the values lower than the median and have been considered as low incidence years in the ROC process. Alternatively the values greater than the median have been considered as high incidence years. The crosses depict missing values.