Graphical representation of Data in Research

1. GRAPHICAL
PRESENTATION OF DATA
BA R , PI E , LI N E G R A P H S , HI S TO G R A M S

2. BAR GRAPH

3. INTRODUCTION
Bar graphs
ØThe pictorial representation of data (generally grouped)
ØIn the form of vertical or horizontal rectangular bars,
Øwhere the length of bars are proportional to the measure of data.
ØAlso known as bar charts.
ØBar graphs are one of the means of data handling in statistics.
ØHelps to compare the different sets of data among different groups easily.
Øshows the relationship using two axes, in which the categories on one axis and the discrete
values on the other axis.
ØTwo types: Horizontal Bar Graphs & vertical Bar Graphs

4. To represent this data on a horizontal bar graph:

5. EXAMPLE
Table 1: No. of Books Issued in 0neWeek
Days No. Of Books
Issued
1 14
2 18
3 20
4 25
5 28
6 30
7 31
14
18
20
25
28
30 31
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7
Number of Books Issued

6. BAR GRAPHS
ADVANTAGES:
v Comparison is made easy and save
time.
v Show each data category in a
frequency distribution
v Make trends easier to highlight than
tables do
v Estimates can be made quickly and
accurately
DISADVANTAGES:
vUse only with discrete data
vLimited space for labeling with vertical
bar graphs
vOften require additional explanation
vFail to expose key assumptions, causes,
impacts and patterns
vCan be easily manipulated to give false
impressions

7. PIE
CHARTS
24%
73%
2% 1%
KUK Central Library Users
U.G Students P.G Students
Research Scholars Teaching Staff

8. PIE CHARTS
• A pie chart is a type of graph that represents the data in the circular graph.
• also known as “circle chart”
• Divides the circular statistical graphic into sectors or slices in order to
illustrate the numerical problems.
• Each pie section should have a label and percentage

9. CALCULATION OF PIE CHART
• The total value of the pie is always 100%.
• To work out with the percentage for a pie chart, follow the steps given below:
• Categorize the data
• Calculate the total
• Divide the categories
• Convert into percentages
• Finally, calculate the degrees
• Therefore, the pie chart formula is given as
• (Given Data/Total value of Data) × 360

10. EXAMPLE OF PIE CHART

11. PIE CHART
ADVANTAGES
• Simple and easy-to-understand
• Data can be represented visually as a
fractional part of a whole
• Provides an effective communication tool
for the even uninformed audience
• Helps in data comparison
• Helps in quickly understand information
DISADVANTAGES
• It becomes less effective, if there are too
many pieces of data to use
• If there are too many pieces of data. Even
if you add data labels and numbers may
not help here, they themselves may
become crowded and hard to read
• This chart only represents one data set.

12. LINE GRAPHS

13. LINE GRAPHS
v Graphical display of information that changes
continuously over time
v appropriate when we need to present the
movement or variation in a variable.
v Line graphs can be used for discrete data.
v Types:
• Simple Line Graph: Only one line is
plotted on the graph.
• Multiple Line Graph: More than one line
is plotted on the same set of axes. A
multiple line graph can effectively
compare similar items over the same
period of time.
• Compound Line Graph: If information
can be subdivided into two or more types
of data.

14. EXAMPLE
• Number of books issued in a library
(month- wise for the year 2020)
Months No. of
Visitors
Months No. of
Visitors
January 76 July 105
February 85 August 108
March 86 September 110
April 90 October 115
May 82 November 118
June 98 December 106

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16. HISTOGRAM

17. HISTOGRAM
• A histogram is a graphical representation of a grouped frequency distribution
with continuous classes..
• Defined as a set of rectangles with bases along with the intervals between class
boundaries and with areas proportional to frequencies in the corresponding
classes

18. STEPS OF MAKING
HISTOGRAM
q The steps followed are:
Ø On a graph paper mark class intervals such as 100-200,
200-300, etc. on the horizontal axis.
Ø Similarly mark frequencies on the vertical axis.
Ø draw rectangles as shown in Figure next page
Ø When class intervals are equal the height of rectangles are
equal to the frequency of classes.
Ø When class intervals are not equal the frequencies are
adjusted so that area of rectangle is proportional to class
frequency.
Ø For example, if the interval of one class is double that of
other classes, then we need to divide the frequency of the
former by two.

19. EXAMPLE
Class
Interval
Frequency Relative Frequency
100-200 21 12.00
200-300 32 18.29
300-400 49 28.00
400-500 33 18.86
500-600 23 13.14
600-700 12 6.86
700-800 5 2.86
Total 175 100.00
Table 1: Monthly Expenditure on Purchase of
Books (in Rupees)
Figure 1: Monthly Expenditure on Purchase of
Books

20. HISTOGRAM
ADVANTAGES
• Visually strong
• Can compare to normal curve
• Vertical axis is a frequency count of items
falling into each category.
DISADVANTAGES
• Cannot read exact values because data is
grouped into categories
• More difficult to compare two data sets
• Use only with continuous data

21. DIFFERENCE BETWEEN HISTOGRAM &
BAR- GRAPH
Histogram Bar Graph
It is a two-dimensional figure It is a one-dimensional figure
The frequency is shown by the area of each
rectangle
The height shows the frequency and the width has no
significance.
It shows rectangles touching each other It consists of rectangles separated from each other with
equal spaces.