Figure 3. Univariate cumulative sum (CUSUM) and EXPO algorithm flags for each chief complaint and emergency department diagnosis category for 2005–2006. Gray and black lines denote observed daily counts for the complaint and diagnosis data, respectively. Gray and black symbols denote the algorithm flags (capital letters = EXPO flags; lowercase letters = CUSUM flags and v = viral illness; p = pneumonia; u = URI; g = gastrointestinal).