Timing of Surveillance Tree signals for 2009 test data. The solid black line in this figure gives the daily, smoothed number of presentations observed overall over 2009. The dashed line gives the smoothed day-ahead forecasts of the expected count. The coloured tick marks along the bottom of the diagram indicate when the Surveillance Tree system has signalled. At one end of the colour spectrum, a blue bar indicates one tree branch was left after pruning, at the red end of the spectrum there where 7 branches left.