Presentation of Data

Charts and diagrams

• Their purpose is to display data in a way that

can be quickly and easily understood.

Charts and diagrams:

• Bar charts

Simple bar

Multiple bar

Component bar

• Histogram

• Pie diagram

• Line diagram

Bar chart

• A bar chart is a way of summarizing a set of categorical data.

• It displays the data using a number of rectangles, of the same

width, each of which represents a particular category.

• The length (and hence area) of each rectangle is proportional

to the number of cases in the category it represents, for

example, age group, religious affiliation

• Bar charts are used to summarize nominal or

ordinal data

• Bar charts can be displayed horizontally or

vertically and they are usually drawn with a

gap between the bars (rectangles)

Types of bar chart

• A simple bar chart is used to represents data

involving only one variable

• In simple bar chart, we make bars

of equal width but variable length, i.e. the

magnitude of a quantity is represented by the

height or length of the bars.

Multiple bar chart

• By multiple bars diagram two or more sets of

inter-related data are represented (multiple

bar diagram facilities comparison between

more than one phenomena).

• we use different shades, colors, or dots to

distinguish between different phenomena.

Component bar chart• Sub-divided or component bar chart is used to represent data in

which the total magnitude is divided into different or components.

• In this diagram, first we make simple bars for each class taking

total magnitude in that class and then divide these simple bars

into parts in the ratio of various components.

• This type of diagram shows the variation in different components

within each class as well as between different classes.

• Sub-divided bar diagram is also known as component bar chart or

staked chart.

Histogram • A histogram is a way of summarizing data that are measured

on an interval scale (either discrete or continuous).

• It divides up the range of possible values in a data set into

classes or groups.

• For each group, a rectangle is constructed with a base

length equal to the range of values in that specific group,

and an area proportional to the number of observations

falling into that group.

• The histogram is only appropriate for variables

whose values are numerical and measured on

an interval scale.

• It is generally used when dealing with large

data sets

Pie diagram

• A pie chart is a way of summarizing a set of

categorical data.

• It is a circle which is divided into segments.

Each segment represents a particular category.

• The area of each segment is proportional to the

number of cases in that category

Line diagram

• A line chart or line graph is a type of chart which

displays information as a series of data points

connected by straight line segments.

• It is a basic type of chart common in many fields.

• A line chart is often used to visualize a trend in data

over intervals of time – a time series– thus the line is

often drawn chronologically.

Thank you