graph methodology

1. Graphical Representation of Experimental
Data
Helal Uddin Mullah
Research Scholar (ECE)
mullahz251@gmail.com
Department of Electronics and Communication Engineering
Tezpur University, Napaam
Sonitpur- 784028
September 22, 2015
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 1 / 15

2. Contents
Introduction
Inventor of Graphs
Types of Graphs
Line Graph
Polygraph
Bar graphs
Pie graphs
Conclusion
references
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 2 / 15

3. Introduction
A Graphical representation is a visual display of data and
statistical results. It is more often and eective than presenting
data in tabular form.
There are dierent types of graphical representation and which are
used depending on the nature of the data and the nature of the
statistical results.
Graphical representation helps to quantify, sort and present data
in a method that is understandable to a large variety of audience.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 3 / 15

4. Inventor of Graphs
William Playfair (1759-1823), Scottish engineer and political
economist, is the principal inventor of statistical graphs.
In 1786, he published Commercial and Political Atlas that
contained 44 charts.
He invented the three basic forms of graph:
The statistical line graph,
The bar graph,
The pie graph.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 4 / 15

5. Types of Graphs
Line graphs
Bar graphs
Pie graphs
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 5 / 15

6. Line Graphs
A graph showing the dierences in frequencies or percentages
among categories of an interval-ratio variable
Points representing the frequencies of each category are placed
above the midpoint of the category and are joined by a straight
line.
Line graph are usually drawn to represent the time series data.
E.g. Temparature, Rain fall, Population growth, Birthrates etc.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 6 / 15

7. Polygraph
Polygraph is a line graph in which two or more than two variables
are shown on a same diagram by dierent lines.
It helps in comparing the data.
Examples which can be shown as polygraph are:
The growth rate of dierent crops like rice, wheat in one diagram.
The birth rates, death rates and life expectancy in one diagram.
Sex ratio in dierent states or countries in one diagram.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 7 / 15

8. Bar Graphs
A Bar graph is a chart with rectangular bars with length
proportional to the values that they represent. The bars can be
plotted vertically or horizontally.
Bar graphs are used to show a comparison of multiple objects. One
axis of the chart shows the specic categories being compared, and
the other axis represents discrete values.
Following rules were obeyed while constructing a bar diagram:
The width of all the bars or columns is similar.
All the bars should be placed on equal intervals/distance.
Bars are shaded with colours or patterns to make them distinct and
attractive.
Three Types of Bar graphs are used to represent dierent data
sets:
The simple bar diagram
Compound bar diagram
Polybar diagram
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 8 / 15

9. 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.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 9 / 15

10. Compound bar diagram
When dierent components are grouped in one set of variable or
dierent variables of one component are put together, their
representation is made by a compound bar diagram.
In this method, dierent variables are shown in a single bar with
dierent rectangles.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 10 / 15

11. Polybar diagram
The line and bar graphs as drawn separately may also be combined
to depict the data related to some of the closely associated
characteristics such as the climatic data of mean monthly
temperatures and rainfall.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 11 / 15

12. Histogram
Histograms are diagrams of frequency distribution for continous
data.
Width of bars represent class intervels and height represents
corresponding freequency.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 12 / 15

13. Pie Graphs
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.
Compares sub classes or categories to the whole class or categories
using dierently coloured or patterned segments
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 13 / 15

14. Conclusion
If the information is presented in tabular form or in a descriptive
record, it becomes dicult to draw results.
Graphs help us in visualizing numerical data.
The graphic method of the representation of data enhances our
understanding.
It makes the comparisons easy.
Besides, such methods create an imprint on mind for a longer time.
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 14 / 15

15. The End
Thank You !
Helal Uddin Mullah (Ph.D, ECE) (Department of Electronics and Communication EngineeringTezpur UniversGraphing Experimental Data September 22, 2015 15 / 15