This document provides instructions on how to construct line graphs and polygraphs to represent time series and comparative data. It explains that line graphs are used to plot one variable over time, such as temperature, rainfall, or population growth. The data should be simplified, axes labeled, an appropriate scale chosen, and data points plotted and connected. A polygraph can show two or more variables on the same graph using different lines to allow comparison, such as comparing crop growth, birth/death rates, or sex ratios in different places. An example is given of constructing a polygraph to compare sex ratios in different states using sample data provided in a table.

1. Dr. V. Vadivel
Assistant Professor
PG & Research Department of Botany
V.O. Chidambaram College
Tuticorin – 628 008
drvvadivel@gmail.com

43.  The line graphs are usually drawn to represent the time series data
 Example:
 Temperature,
 Rainfall,
 Population growth,
 Birth rates and
 the death rates.

44. • Simplify the data by converting it into round numbers.
• Example
• Growth rate of population shown in Table may be rounded to
2.0 and 2.2 respectively.
• Draw X and Y-axis.
• Mark the time series variables (years/months) on the X axis and
the data quantity/value to be plotted (growth of population in per
cent) on Y axis.
• Choose an appropriate scale and label it on Y-axis. If the data
involves a negative figure then the selected scale should also show
it as shown in figure.
• Plot the data to depict year/month-wise values according to the
selected scale on Y-axis, mark the location of the plotted values by
a dot and join these dots by a free hand drawn line.

46. Construct a line graph to represent the data as given in Table

48. • Polygraph is a line graph in which two or more than two variables
are shown on a same diagram by different lines.
• It helps in comparing the data.
• Examples which can be shown as polygraph are:
• The growth rate of different crops like rice, wheat, pulses in one
diagram.
• The birth rates, death rates and life expectancy in one diagram.
• Sex ratio in different states or countries in one diagram.

49. Construct a polygraph to compare the growth of sex-ratio in
different states as given in the Table
Sex-Ratio (Female per 1000 male) of Selected Sates – 1961-2001

50. Polygraph