Following aspects must be considered while constructing statistical diagrams or graphs for representing information:
1. Sources of Information/Data:
- Data to analysis is like food to body, better the quality of data, finer the analysis and decision making.
- One should take care that the sources of data are reliable and universally acceptable so that its accuracy can be ensured.
- ‘Economic Survey of India’ and data provided by Central Statistical Organization are considered quite reliable source to obtain information re¬garding growth and development parameters in India.
- ‘World Development Report’ is a reliable and universally acceptable source to obtain data for comparing parameters such as growth and development of various countries of the world.
2. Clarity regarding dependent and independent variable:
In general, data pertaining to the independent variable must be represented on the X-axis and that pertaining to the dependent variable must be represented on the Y-axis.
(a) While studying cause-effect relationship between variables, the cause variable is treated as an independent variable and the effect variable is treated as a dependent variable as its values are dependent on the values of the independent variable.
(b) If we are examining the relationship between rainfall and agricultural production in a region, then rainfall is the independent variable and is represented on X-axis whereas agricultural production is the dependent variable and therefore represented on the Y-axis.
(c) Time is an independent variable. So, if we are examining production over different time periods then time period is represented on X-axis and produc¬tion on Y-axis.
Note that in economics while studying the law of demand, price which is an independent variable is represented on the Y-axis and demand which is a dependent variable is represented on X-axis.
3. Selecting appropriate scales:
- Scales are measures taken to represent actual data in a diagram.
- Taking proper scales on both the axis are very important in order to obtain a systematic graph with clarity and appropriate size,
- If actual data is too large, say in ’00 i.e. hundreds or in ‘00000 i.e. lakhs then such data cannot be directly represented in charts. Hence, such data is represented after converting it into measures on an appropriate scale.
You must have seen in diagrams and maps showing distance of 1 cm = 10,000 units or 1 cm = 5 years and so on. Such scales are taken on both the axis.