Graphical representation

 

Significance, Types and Construction of Diagrams and Graphs

Significance of Diagrams and Graphs:

Diagrams and graphs are extremely useful because of the following reasons.

1. They are attractive and impressive.
2. They make data simple and intelligible.
3. They make comparison possible
4. They save time and labour.
5. They have universal utility.
6. They give more information.
7. They have a great memorizing effect.

Types of Diagrams and Graphs

One of the most effective and interesting alternative ways to present statistical data 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 most commonly used diagrams and graphs shall be discussed in subsequent posts, as listed below.

Types of Diagrams/Charts

1. Simple Bar Chart
2. Multiple Bar Chart or Cluster Chart
3. Stacked Bar Chart or Sub-Divided Bar Chart or Component Bar Chart
   • Simple Component Bar Chart
   • Percentage Component Bar Chart
   • Sub-Divided Rectangular Bar Chart
   • Pie Chart

Types of Diagrams/Charts

1. Histogram
2. Frequency Curve and Polygon
3. Lorenz Curve
4. Historgram

Construction of Diagrams and Graphs

The following general rules should be observed while constructing diagrams:

1. Title: Every diagram must be given a suitable title. The title should convey in as few a words as possible the main idea that the diagrams intent to portray. However, the brevity should not be secured at the cost of clarity or omission of essential details. The title may be given either at the top of the diagram or below it.
2. Proportion between width and height: A proper proportion between the height and width of the diagram should be maintained. If either the height and width is too short or too long in proportion, the diagram would given an ugly look. While there are no fixed rules about the dimensions, a convenient standard as suggested by Lutz in the book entitled “Graphic Presentation” may be adopted for general use. It is known as “Root-two”, that is, a ratio of 1 (short side) to 1.414 (long side). Modifications may, no doubt, be made to accommodate a diagram in the space available.
3. Selection of scale: The scale showing the values may be in even numbers or in multiples of five or ten, eg. 25, 50, 75, or 20, 40, 60. Odd values like 1, 3, 5, 7 may be avoided.
4. Footnotes: In order to clarify certain points about the diagram, footnote may be given at the bottom of the diagram.
5. Index: An index illustrating different types of lines or different shades, colours should be given so that the reader can easily make out the meaning of the diagram.
6. Neatness and cleanliness: Diagrams should be absolutely neat and clean.
7. Simplicity: Diagrams should be as simple as possible so that the reader can understand their meaning clearly and easily. For the sake of simplicity, it is important that too much material should not be loaded in a single diagram otherwise it may become too confusing and prove worthless. Several simple charts are often better and more effective than one or two complex ones which may present the same material in a confusing way.