Technical Guidelines for Integrated Disease Surveillance ... - PHRplus

Figure 2: Weekly trend of cholera in Accra Metropolis June-August 2001 comparedwith same period 2000Bar graphs also can be used to display the number of cases over time. Figure 3 is an example of a bar graph.Figure 3: Number of cases by day of onset of symptomsA histogram is like a line graph except that it uses squares to represent cases rather than a line to connectplotted points. Use histograms to analyse outbreak data and to show an epidemic curve (an epi curve). For acuteoutbreak diseases, time may be shown in one-day, two-day, three-day, one-week or longer intervals. In a histogram,the cases are stacked on the graph in adjoining columns. Figure 4 is an example of a histogram.Section 3: Analyse Data33