Graphical representation of data mohit verma

GRAPHICAL
REPRESENTATION OF
DATA
Submitted by
Mohit Kumar Verma
(Pharmacology 1st Year)
Dept. of Pharmaceutical Science1

CONTENTS
• Introduction
• Types of graphical representations of data
• Types of diagrams
• The Simple Bar Diagram
• Multiple Bar Diagram
• Pie Diagram
• Compound Bar Diagram
• The histogram
• The need of graphically representing data
• References
2

INTRODUCTION
• Graphical Representations of Data
• “The transformation of data through visual methods like graphs,
diagrams, maps and charts is called representation of data.”
• Visualization techniques are ways of creating and manipulating
graphical representations of data. We use these representations in
order to gain better insight and understanding of the problem.
• Pictures can convey an overall message much better than a list of
numbers. Lets we now discuss some graphical presentations of
data.
3

Types of Graphical Representations of data
1. GRAPHS OF FREQUENCY DISTRIBUTION
2. GRAPHS OF TIME SERIES OR LINE GRAPHS
1. Graphs of frequency distribution
Frequency distribution can be represented graphically. Such as
graphs give a better picture when the data are arranged in tabular
form. Types of Frequency distribution graphs.
 The Histogram
 The Frequency Polygon
 The Frequency Curve
 Cumulative Frequency curve. 4

Types of Diagrams
• The diagrams are of following types:
• (i) One-dimensional diagrams such as line graph, poly graph, bar
diagram, histogram etc.
• (ii) Two-dimensional diagram such as pie diagram and rectangular
diagram.
• (iii) Three-dimensional diagrams such as cube and spherical
diagrams.
5

The most commonly drawn diagrams are:
1. Line graphs 2. Bar diagrams 3. Pie diagram
1. Line Graphs
The line graphs are usually drawn to represent the time series data
related to the temperature, rainfall, population growth, birth rates
and the death rates.
Construction of a Line Graph
1st step: Draw X and Y-axis. Mark the time series variables
(years/months) on the X axis and the data quantity/value to be
plotted on Y axis.
6

• 2nd step: Choose an appropriate scale to show data and label it on Y-
axis. If the data involves a negative figure then the selected scale
should also show it. Example;
Classes 0-10 10-20 20-30 30-40 40-50 50-60
Frequency 6 12 16 18 8 4
0
2
4
6
8
10
12
14
16
18
20
1 2 3 4 5 6
Frequency
Frequency
7

2. Bar Diagram
It is also called a columnar diagram. The bar diagrams are drawn
through columns of equal width. Following rules were observed while
constructing a bar diagram:
(a) The width of all the bars or columns is similar.
(b) All the bars should are placed on equal intervals/distance.
(c) Bars are shaded with colours or patterns to make them distinct and
attractive . Four types of bar diagrams are used to represent different
data sets:
1. The simple bar diagram 2. Compound bar diagram
3. Multiple bar diagram 4. Poly bar diagram. 8

The simple bar diagram
• A simple bar diagram is constructed for an immediate comparison. It
is advisable to arrange the given data set in an ascending or
descending order and plot the data variables accordingly. However,
time series data are represented according to the sequencing of the
time period.
Construction Steps:
• Draw X and Y-axes on a graph paper. Take an interval and mark it on
Y-axis to plot data.
• Divide X-axis into equal parts to draw bars. The actual values will be
plotted according to the selected scale.
9

0
2
4
6
8
10
12
14
16
18
20
1 2 3 4 5 6
Simple bar diagram
FREQUENCY
cClasses 0-10 10-20 20-30 30-40 40-50 50-60
Frequency 6 12 16 18 8 4
Example ;
10

Multiple Bar Diagram
• Multiple bar diagrams are constructed to represent two or more than
two variables for the purpose of comparison. For example, a multiple
bar diagram may be constructed to show proportion of males and
females in the total.
• Construction
(a) Mark time series data on X-axis and variable data on Y-axis as per
the selected scale.
(b) Plot the data in closed columns.
11

cClasses 5 15 25 35 45 55
Frequency 6 12 16 18 8 4
Example ;
0
10
20
30
40
50
60
1 2 3 4 5 6
cClasses
Frequency
12

3. Pie Diagram
• Pie diagram is another graphical method of the representation of
data. It is drawn to depict the total value of the given attribute using
a circle. Dividing the circle into corresponding degrees of angle then
represent the sub– sets of the data. Hence, it is also called as
Divided Circle Diagram. The angle of each variable is calculated
using the following formulae.
Value of given state/ Region X 360
Total Value of all States / Regions
13

If data is given in percentage form, the angles are calculated using
the given formulae.
Percentage of x X 360
100
Calculation of Angles
(a) Arrange the data on percentages in an ascending order.
(b) Calculate the degrees of angles for showing the given
values
(b) It could be done by multiplying percentage with a
constant of 3.6 as derived by dividing the total number of
degrees in a circle by 100, i. e. 360/100.
14

• Example;
cClasses 5 15 25 35 45 55
Frequency 6 12 16 18 8 4
3%
8%
14%
19%
25%
31%
Classes
1 2 3 4 5 6
15

Compound Bar Diagram
When different components are grouped in one set of variable or
different variables of one component are put together, their
representation is made by a compound bar diagram. In this method,
different variables are shown in a single bar with different rectangles.
Construction
(a) Arrange the data in ascending or descending order.
(b) A single bar will depict the set of variables by dividing the total
length of the bar as percentage.
16

0
2000
4000
6000
8000
10000
12000
FOOD CLOTHE HOUSE RENT FUEL AND
ELECTRICSITY
MISCELLANEOUS TOTAL
Family B
Family A
FOOD 1800 2200
CLOTHING 600 1000
HOUSE RENT 1000 2000
FUEL AND ELECTRICSITY 400 500
MISCELLANEOUS 200 300
TOTAL 4000 6000
Example:
17

Histogram
• A histogram is used for continuous data, where the bins
represent ranges of data, and the areas of the rectangles are
meaningful, while a bar chart is a plot of categorial variables
and the discontinuity should be indicated by having gaps
between the rectangles, from which only the length is
meaningful.
18

0
2
4
6
8
10
12
14
16
18
20
1 2 3 4 5 6
CLASSES
FREQUENCY
HISTOGRAM
cClasses 10 20 30 40 50 60
Frequency 6 12 16 18 8 4
Example :
19

The need of graphically representing data :
• Graphics, such as maps, graphs and diagrams, are used to represent
large volume of data.
• If the information is presented in tabular form or in a descriptive
record, it becomes difficult to draw results.
• Graphical form makes it possible to easily draw visual impressions
of data.
• It is a time consuming task to draw inferences about whatever is
being presented in non–graphical form.
• These makes it easy to understand the patterns of population
growth, distribution and the density, sex ratio, age–sex composition,
occupational structure, etc.
20

References
1. Kumar Arun pharmaceutical biostatics published by Krishna
prakashan media Ltd. Second edition 2011 Page no. 49-65.
2. http://s3.amazonaws.com/pdf
download/graphicalrepresentationofdata-151013151149-lva1
accessed on 24 Feb, 2016 at 1:17 am.
21

Graphical representation of data mohit verma

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