Trainer Attachment 13F: Visualization of numerical data

To understand the significance of and reasons for collecting data, it must be interpreted and presented in a form that is clearly understandable by the persons who will be using this data to determine:

- the program's effectiveness in achieving its objectives,
- to reevaluate goals
- to seek program support (monetary, staffing, etc.)

A useful way of presenting data is through a graph. A graph should be used to give an impression, indicate a trend or change or convey a sense of movement of the data.

The purpose of Step 8 in this session is for you to present and explain the different types of graphs that the participants should develop to analyze their data and later to monitor their programs performance. Based on your presentation, the participants will practice using these different graphic formats in Step 10.

Several types of formats that you should include in your presentation are a line graph, bar graph and map or area graph.

Explanations and examples of these formats have been appended to this attachment. Suggested discussion questions have also been included.

Regardless of the format all graphs must have a title that is clear and gives the name of the disease and the location and date of the event you are recording. Also the axes should be fabled. Time is often written on the horizontal axis and rates are written on the vertical line.

Line Graph

The line graph is a functional technique to employ when displaying the overall movement of numerical data over a definite period of time. Using thin format, large amounts of data can be presented in a single display - the flow of events over centuries can be visualized with as much clarity as events occurring within the past twelve months. The line graph is a format that can demonstrate the fluctuations, highs and lows, rapid or slow movements, or relative stability of statistics. In addition, the line graph is an excellent format to utilize when comparisons and relationships need to be communicated. Line graphs can incorporate two, three, four, or more scales to compare the same item in different time periods.

Measles Cases Reported to Health Center Coro, by Month, 1982

1. Ask the participants to identify which month has the most cases and which the fewest.

Bar Graph

The bar graph is one of the most convenient and widely used formats for displaying numerical data. The length of a bar corresponds to an item's value or amount. When a second bar is added, a comparison becomes possible. As more bars are added, more comparisons are possible.

There is a distinction between a horizontal bar graph and a vertical bar graph. The horizontal bar graph, with bars lined up horizontally, usually deals with different items compared during the same period of time. The horizontal bar graph is arranged so that items compared are listed on the vertical axis, and the quantity or amount scale is listed on the horizontal axis.

The vertical bar graph, deals with similar items compared at different periods of time. The vertical bar graph lists the amount scale on the vertical axis and time on the horizontal axis.

Immunizations Given in One Month at Health Center Mopti

1) What does this indicate about the vaccination coverage in each region?

Diarrhea Cases Reported to Health Center in Kaffrine by Sex and Age

1) Is the total number of cases of diarrhea greater for females than males?
2) Does the graph indicate which group is at higher risk of diarrhea?

Map/Area Graph

Maps can serve as more than a conventional geographic reference' they offer a versatile and functional way of displaying numerical data.

The map graph sometimes falls in the pictorial graph category. If thought of in this sense, the map can be employed as a backdrop for data or as an integral part of the data. In either case, whether local, state, national or international in nature, the presence of a map suggests to the viewer a geographical frame of reference as in Figure 1.

In Figure 1 the map is employed to analyze information about place of occurrence of disease. The viewer can see area trends.

The area graph divides the whole into its parts. Concrete or abstract shapes can be employed.

Analysis of Information about PLACE.

Analysis of information about Place often requires mapping. Mapping shows where the households with cases are located in a village, or where the villages with cases are found in a region. To map, circle the location of the households or the villages which contain cases on a map of the village or region, and in the circle, write the number of cases. If a map is not already available, you might need to draw one yourself after studying the village or region. Attached is an example for measles use.

Measles cases by village April-May 1983

1. Ask the group if the cases appear to be more numerous in certain location.

Tell the group there have been several measles immunizations in Villages A, B, C and E. Ask them to identify if there are any villages or towns in which they would suspect that immunizations had not been effective.