We can put graphical representation of frequancy distribution in any of the following ways.
(1) Histogram or Area Diagram or Column Diagram.
(2) Frequency Polygon.
(3) Frequency Curve.
(4) Cumulative Frequency Curve or Ogive.
(1) Histogram : It represents mode graphically.To plot this data should be continuous.In this class intervals are
plotted on x axis and their respective frequency on y axis.
Note : When class intervals are not equal first calculate
frequency density (FD).
F.D =
frequency of the class x width of the smallest class interval
/
width of the class interval
or
F.D =
frequency of the class
/
Adjustment factor
AF =
width of the class interval
/
width of the smallest class interval
(2) Frequency Polygon :- Frequency polygon is a graphical representation of data in which the mid-point of
each classes is taken on x-axis and corresponding frequencies are placed on y axis , joined all the mid-points by line segment. It
can also be drawn by constructing a histogram.
(3) Frequancy Curve :- It is similar to frequancy polygon,
only difference is that the points are joined by drawing a smooth curve or free hand curve. The total area is taken to be unity. It is a limiting
form of a histogram or frequancy polygon.
There are four types of frequancy curves
(a) Bell-Shaped Curve
:- Commonly used distributions provides bell-shaped curve. Distributio related height, weight, mark, profit, et belong to this category.
(b) U-Shaped Curve
(c) J-Shaped Curve
(d) Mixed Curve : This may have a combination
of above three curved.
(4) Cumulative Frequency Curve or Ogive Curve :- There are two type of ogive curves less than
type ogive curve and more than type ogive curve . The intersection of both ogive curves gives Median of the given data.
(a) Less than Ogive Curve : In this less than frequancy is used that is plotted on y-axis and upper limit of the class interval plotted
on x-axis. It is a increasing curve, having S-shape.
(b) More than Ogive Curve: In this more than frequancy
is used that is plotted on y-axis and lower limit of the class interval plotted on x-axis. It is a decreasing curve.
