Types of diagrams and Graphs:
One of the most effective and interesting alternative way in which a statistical data may be presented is through diagrams and graphs. There are several ways in which statistical data may be displayed pictorially such as different types of graphs and diagrams. The commonly used diagrams and graphs to be discussed in subsequent paragraphs are given as under.
Types of Diagrams/Charts:
1. Simple Bar Chart
2. Multiple Bar Chart or Cluster Chart
3. Staked Bar Chart or Sub-Divided Bar Chart or Component Bar Chart
4. Simple Component Bar Chart
5. Percentage Component Bar Chart
6. Sub-Divided Rectangular Bar Chart
7. Pie Chart
Types of Diagrams/Charts:
1. Histogram
2. Frequency Curve and Polygon
3. Lorenz Curve
4. Historigram
Difference Between Diagrams And Graphs
There is no clear-cut line of demarcation between a diagram and a graph yet:
1. A graph needs a graph paper but a diagram can be drawn on a plain paper. In the technical way we can say that a graph is amathematical relation between two variables. This however is not the case of a diagram.
2. As diagrams are attractive to look at, they are used for publicity and propaganda. Graphs on the other hand are more useful to statisticians and research workers for the purpose of further analysis.
3. For representing frequency distribution, diagrams are rarely used when compared with graphs. For example, for the time series graphs are more appropriate than diagrams.
Uses of Diagrams and Graphs:
Diagrams and graphs are extremely useful due to the following reasons:
1. Information presented though diagrams and graphs can be understood easily just in a bird’s eye view.
2. These are appealing and fascinating to the eyes; Scholars take greater interest in presenting data through these devices.
3. Diagrams and graphs produce a greater lasting impression on the mind of the readers than the figures presented in a table.
4. They facilitate ready comparison of data over time and space. Graphs study economic relationship between two variables.
However, graphic and diagrammatic presentation have some limitations. For example, unlike a table a diagram or a graph does not show the exact value of a variable. Further, a limited set of facts can be presented through such devices like diagram and graph.
General Rules for Drawing Graphs and Diagrams
Following points must be kept in mind while constructing a diagram or graph. Every diagram or graph must have a serial number. It is necessary to distinguish one from the other.
1. Serial number: Every diagram or graph must have a serial number. It is necessary to distinguish one from the other.
2. Title: Title must be given to every diagram or graph. From the title one can know the idea contained in it. The title should be brief and self-explanatory. It is usually placed at the top.
3. Proper size and scale: A diagram or graph should be of normal size and drawn with proper scale. The scale in a graphs specifies the size of the unit.
4. Cleanliness: Diagrams must be as simple as possible. Further they must be quite neat and clean. They should also be descent to look at.
5. Index: Every diagram or graph must be accompanied by an index. This illustrates different types of lines, shades or colors used in the diagram.
6. Footnote: Foot notes may be given at the bottom of a diagram if necessary. It clarifies certain points in the diagram.