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Introduction |
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Facts and figures as such do not catch our attention unless they are presented in an interesting way. Graphical representation of data is one of the most commonly used modes of presentation. The different types of graphs that we are going to study are
1. Bar graphs
2. Pie charts
3. Frequency polygon
4. Histogram. |
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Graphical Representation of Data |
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The graphical representation of data makes the reading more interesting, less time-consuming and easily understandable. The disadvantage of graphical presentation is that it lacks details and is less accurate. In our study, we have the following graphs:
1. Bar Graphs
2. Pie Charts
3. Frequency Polygon
4. Histogram. |
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Bar Graphs |
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This is the simplest type of graphical presentation of data. The following types of bar graphs are possible:
(a) Simple bar graph
(b) Double bar graph
(c) Divided bar graph. |
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Pie Graph or Pie Chart |
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Sometimes a circle is used to represent a given data. The various parts of it are proportionally represented by sectors of the circle. Then the graph is called a Pie Graph or Pie Chart. |
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Frequency Polygon |
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In a frequency distribution, the mid-value of each class is obtained. Then on the graph paper, the frequency is plotted against the corresponding mid-value. These points are joined by straight lines. These straight lines may be extended in both directions to meet the X - axis to form a polygon. |
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Histogram |
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A two dimensional frequency density diagram is called a histogram. A histogram is a diagram which represents the class interval and frequency in the form of a rectangle. |
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Summary |
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1. In a simple bar graph, the height of each bar represents the frequency.
The thickness has no significance. All bars to have the same thickness. |
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2. We use double bar graph when we want to compare two things. |
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3. In the frequency polygon, the frequency is plotted against the mid value of each class. These points are joined by line segments.
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