graphing experimental result

Graphical Representation of Experimental

Data

Helal Uddin Mullah

Research Scholar (ECE)

[email protected]

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 University, Napaam Sonitpur- 784028 )Graphing Experimental Data September 22, 2015 1 / 15

Contents

Introduction

Inventor of Graphs

Types of Graphs

Line Graph

Polygraph

Bar graphs

Pie graphs

Conclusion

references


Introduction

A Graphical representation is a visual display of data and

statistical results. It is more often and e�ective than presenting

data in tabular form.

There are di�erent 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.


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.


Types of Graphs

Line graphs

Bar graphs

Pie graphs


Line Graphs

A graph showing the di�erences 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.


Polygraph

Polygraph is a line graph in which two or more than two variables

are shown on a same diagram by di�erent lines.

It helps in comparing the data.

Examples which can be shown as polygraph are:

The growth rate of di�erent crops like rice, wheat in one diagram.The birth rates, death rates and life expectancy in one diagram.Sex ratio in di�erent states or countries in one diagram.


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 speci�c 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 andattractive.

Three Types of Bar graphs are used to represent di�erent datasets:

The simple bar diagramCompound bar diagramPolybar diagram


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.


Compound bar diagram

When di�erent components are grouped in one set of variable or

di�erent variables of one component are put together, their

representation is made by a compound bar diagram.

In this method, di�erent variables are shown in a single bar with

di�erent rectangles.


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.


Histogram

Histograms are diagrams of frequency distribution for continous

data.

Width of bars represent class intervels and height represents

corresponding freequency.


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 di�erently coloured or patterned segments


Conclusion

If the information is presented in tabular form or in a descriptive

record, it becomes di�cult 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.


The End

Thank You !
