Veterinary Epidemiology and Zoonosis

LINE DIAGRAM

• The frequency of a continuous or discrete variable is presented by a point at a height above the horizontal axis.
• The points are joined by straight lines.
• In line diagrams, it is essential for the scale of vertical axis to begin at zero.
• If the range of values on this axis is so large that it cannot be fitted onto a scale. Which begins at zero, the axis is interrupted by a space so that reader’s attention is drawn to this fact.
• Extension of the line beyond the two extreme points at either end is known as extrapolation and it should not be done.
• It is the simplest and most frequently used method of displaying the epidemiology data.
  • Example: Season wise mortality percentage in poultry based on post-mortem examination (1988 – 1997) from Avian Disease Diagnostic Laboratory, Namakkal, Tamilnadu, India. 

Representation of data as "LINE DIAGRAM"