Graphical Representation of Data
☞ (Paste Examples of any graphs, diagrams and maps showing different types of data. For example, relief map, climatic map, distribution of soils maps, population map) REPRESENTATION OF DATA Besides the tabular form, the data may also be presented in some graphic or diagrammatic form. “The transformation of data through visual methods like graphs, diagrams, maps and charts is called representation of data.” The need of representing data graphically: Graphics, such as maps, graphs and diagrams, are used to represent large volume of data. They are necessary: • If the information is presented in tabular form or in a descriptive record, it becomes difficult to draw results. • Graphical form makes it possible to easily draw visual impressions of data. • The graphic method of the representation of data enhances our understanding. • It makes the comparisons easy. • Besides, such methods create an imprint on mind for a longer time. • It is a time consuming task to draw inferences about whatever is being presented in non–graphical form. • It presents characteristics in a simplified way. • These makes it easy to understand the patterns of population growth, distribution and the density, sex ratio, age–sex composition, occupational structure, etc. General Rules for Drawing Graphs, Diagrams and Maps 1. Selection of a Suitable Graphical Method Each characteristic of the data can only be suitably represented by an appropriate graphical method. For example, • To show the data related to the temperature or growth of population between different periods in time line graph are used. • Similarly, bar diagrams are used for showing rainfall or the production of commodities. • The population distribution, both human and livestock, or the distribution of the crop producing areas are shown by dot maps. • The population density can be shown by choropleth maps. Thus, it is necessary and important to select suitable graphical method to represent data. 2. Selection of Suitable Scale Each diagram or map is drawn to a scale which is used to measure the data. The scale must cover the entire data that is to be represented. The scale should neither be too large nor too small.
Graphical Representation of Data
3. Design The diagram or map should have following design: • Title: The title of the diagram/map must be clear and include o The name of the area, o Reference year of the data used and o The caption of the diagram.
These are written with different font sizes and thickness. The title, subtitle and the corresponding year is shown in the centre at the top of the map/diagram. • Legend or Index: The index must clearly explain the colours, shades, symbols and signs used in the map and diagram. A legend is shown either at the lower left or lower right side of the map sheet. Direction The maps should show the direction North and properly placed on the top.
Types of Diagrams The diagrams and the maps is of following types: (i) One-dimensional diagrams such as line graph, poly graph, bar diagram, histogram, age, sex, pyramid, etc.; (ii) Two-dimensional diagram such as pie diagram and rectangular diagram; (iii) Three-dimensional diagrams such as cube and spherical diagrams. The most commonly drawn diagrams and maps are: • Line graphs • Bar diagrams • Pie diagram • Wind rose and star diagram • Flow Charts 1. Line Graph The line graphs are usually drawn to represent the time series data related to the temperature, rainfall, population growth, birth rates and the death rates. Construction of a Line Graph 1st step: Round the data to be shown upto the 1 digit of even numbers. 2nd step: Draw X and Y-axis. Mark the time series variables (years/months) on the X axis and the data quantity/value to be plotted on Y axis. 3rd step: Choose an appropriate scale to show data and label it on Y-axis. If the data involves a negative figure then the selected scale should also...
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