GRAPHICAL REPRESENTATION of diagram in Biostatics

1. GRAPHICAL
REPRESENTATION

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GRAPHICAL
REPRESENTATION
GRAPHICAL REPRESENTATION
Visual representation of statistical data in the form of
points, lines, areas, is known as graphical representation.
Such visual representation can be divided in to two
groups.
(i) Graph
(ii) Diagram
The basic difference between a graph and a diagram is that
a graph is a representation of data by a continuous curve,
while a diagram is any other one, two or three dimensional
form of visual representation.

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GRAPHICAL
REPRESENTATION
TYPES OF DIAGRAM
(i) Simple bar chart
(ii) Multiple bar chart
(iii) Component bar chart
(iv) Pie diagrams
SIMPLE BAR CHART
A Simple bar chart consists of horizontal or vertical bars
of equal widths and lengths proportional to the
magnitudes of the observations. The space separating the
bars should not exceed the width of the bar and should
not be less than half of its width. The data when do not
relate to time should be arranged in ascending or
descending order before charting.

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GRAPHICAL
REPRESENTATION
Simple Bar Chart:
A Simple bar diagram to represent the turnover of a company for 5 years
Years 1965 1966 1967 1968 1969
Turnover
(Rupees)
35000 42000 43500 48000 48500

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BAR DIAGRAM SHOWING THE
TURNOVER OF A COMPANY FOR 5
YEARS
0
10000
20000
30000
40000
50000
60000
1965 1966 1967 1968 1969
YEARS
TURNOVER

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GRAPHICAL
REPRESENTATION
MULTIPLE BAR CHART
A Multiple bar chart shows two or more characteristics
corresponding to the values of a common variable in the
form of grouped bars whose lengths are proportional to the
values of the characteristics and each of which is shaded
differently for identification.
COMPONENT BAR CHART
In Component bar chart each bar is divided into two or
more sections. The length of the bar represents the total
and various sections represent the components of total.

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GRAPHICAL
REPRESENTATION
Multiple Bar Chart:
A multiple bar diagram to represent the production of wheat in different
localities of the Punjab for year 1987-1989.
1987 1988 1989
Locality-I 500 600 800
Locality-II 600 700 700
Locality-III 200 400 500
Production in Kg. (thousand)

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Multiple bar diagram of different
localities
0
200
400
600
800
1000
1987 1988 1989
Years
Production
L-I
L-II
L-III

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GRAPHICAL
REPRESENTATION
Component Bar Chart:
A component bar diagram to represent the population of different divisions
of the Pakistan.
Division Both
Sexes
Male Female
Peshaw
ar
64 33 31
Rawalpi
ndi
40 21 19
Sargodh
a
60 32 28
Lahore 65 35 30
Population in Lakhs

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COMPONENT BAR CHART
SHOWING POPULATION OF 4
DIVISIONS
0
10
20
30
40
50
60
70
Peshaw
arR
aw
alpindiSargodha
Lahore
DIVISIONS
POPULATION(IN
LAKH)
Female
Male

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GRAPHICAL
REPRESENTATION
PIE DIAGRAM
A Pie diagram consists of a circle divided into sectors
whose areas are proportional to the various parts into
which the whole quantity is divided. The proportion that
each component part bears to the whole quantity will be
the corresponding proportion of 360o
component Part
Angle = ─────────────── x 360
Whole quantity

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GRAPHICAL
REPRESENTATION
Pie Diagrams:
A Pie diagram to represent the total production of urea fertilizer and its use
on different crops.
Crops Fertilizer Angle of sector
Wheat 75 135
Sugarcane 80 144
Maize 30 54
Lentils 15 27
Total 200 360
Production in thousand (kg)

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Pie Diagram for production of
urea fertilizer
Wheat,
75
Sugarc
ane, 80
Maize,
30
Lentils,
15
Wheat
Sugarcane
Maize
Lentils

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GRAPHICAL
REPRESENTATION
Types of Graphs
(i) Graph of time series or Historigram
(ii) Histogram
(iii) Frequency polygon
(iv) Frequency curve
(v) Cumulative Frequency polygon or Ogive
Historigram
A Historigram is constructed by taking time along X-axis and the value of
the variable along Y-axis. Points are plotted and are then connected by
straight line segments to get the Historigram.

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GRAPHICAL
REPRESENTATION
Histogram
A Histogram consists of a set of adjacent rectangles whose bases are marked
off by class boundaries along the X-axis and whose height are proportional
to the frequencies with respective classes (i.e. frequency along Y-axis).
But in case of unequal class interval adjusted frequency is used in place of
frequency where adjusted frequency is obtained by dividing the frequency to
the class interval.
Frequency Polygon
A Frequency polygon is a graphic form of a frequency distribution, it is
constructed by taking the midpoints along X-axis and class frequency along
Y-axis. Points are plotted and are then connected by straight line segments.
But to get a polygon* add extra class midpoints at both ends of the
distribution with zero frequency so that the polygon does form a closed
figure with the horizontal axis.
* (Polygon is a closed figure having many sides)

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GRAPHICAL
REPRESENTATION
Frequency Curve
A frequency curve is constructed by taking the midpoints along X-axis and
class frequency along Y-axis. Points are plotted and are then connected by free
hand curve.
Cumulative Frequency Polygon or Ogive
A Cumulative frequency polygon is obtained by plotting the cumulated
frequency (along Y-axis) against the upper class boundaries (along X-axis) and
the points are joined by straight line segments. To get a polygon include lower
class boundary of the first class with zero frequency and joined the last point
with the last upper class boundary.
TYPES OF FREQUENCY CURVE
(1) Symmetrical distribution
(2) Skewed distribution Frequency polygon

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Historigram
98 74 68 50
99
172
245
302
98 74 68 50
99
172
245
302
0
100
200
300
400
1929 1930 1931 1932 1933 1934 1935 1936
Years
NoofCars
GRAPHICAL REPRESENTATION