Elementary Statstics

5.2.3.1 Rules for constructing the line graphs on Natural Scale

In constructing a graph of time series on natural scale the following points should be kept in mind :

1. Take the time on the X-axis (horizontal) and the variable on the Y-axis (vertical). The unit of time in which the variable under consideration is measured should be clearly stated in the title eg. an indication should be given as to whether the years are calendar or financial or whether the variable is measured as at a date.
2. Begin Y-axis with zero and select a suitable scale so that the entire data is accommodated in the space available. On the arthmetic scale equal magnitude must be represented by equal distances. This requirement is true for both the X-axis as well as the Y-axis but for each separately. For example, I cm on Y-axis may represent 1,000 units whereas 1” on X-axis may represent gap between 1993 and 1994. The scale should be so chosen that the horizontal axis is longer than the vertical one. If the fluctuations in the variable are too small or if the lowest value of the variable is large, the false base should be used.
3. Corresponding to the time factor plot the value of the variable and join the various points by straight lines (and not with curves). The points on the graph should not be indicated by circles or crosses rather dots should be used so that they disappear into line.
4. Join the various points with straight lines, not curves.
5. If on one graph more than one variable is shown, they should be distinguished by the use of thick, thin, dotted lines, etc. or different colours be used. Every graph should be given a suitable title. The unit of time in which the variable under consideration is measured should be clearly stated in the title, i.e. an indication should be given as to whether the years are calendar or financial or whether the variable is measured as at a date.
6. Lettering on the graph, i.e. indication of years, units, etc. should be done horizontally and not vertically so that in order to read what is written it is not necessary to turn the graph from one side to another.