Bar Graphs: We have seen graphs in the newspapers, television, magazines, books, and so on. The pictorial representation of data in the form of vertical or horizontal bars or rectangular strips of uniform width is known as bar graphs. They are also referred to as bar charts or column charts.

In our daily lives, we encounter a wide range of quantitative and qualitative information, which we can represent using a variety of methods such as bar graphs or bar charts, pie charts, frequency distribution tables, histograms, and so on. These graphs are really a great way to show the relative sizes or quantities. This article will discuss the definition of bar graphs, their types, uses, examples, properties and advantages and disadvantages. Keep reading.

What is a Bar Graph?

A bar graph is a pictorial representation of data in the form of vertical or horizontal bars of uniform width. They can be represented  with equal spacing between them on the horizontal axis (say, the \(X\)-axis), representing the variable. The values of the variable are shown on the vertical axis (say, the \(Y\)-axis), and the heights of the bars depend on the values of the variable.

A bar graph is used to give the comparison between two or more categories. It consists of two or more parallel vertical (or horizontal) rectangles.

Example: The bar graph represented in the figure given below indicates Jyoti’s mathematics marks in the \({1^{st}},\,{2^{nd}}\) and \({3^{rd}}\) term examinations. It helps us to compare her progress easily.

Bar graphs are also be represented using double bars. To compare two sets of data on the same graph, double bar graphs are used.

For example, the below graph gives us a comparative quantity of sales (in \(kg\)) of different fruits on Monday and Tuesday.

How do you use a Bar Diagram?

With the help of bar diagrams, it is easy to compare data sets from different groups. The graph represents categories on one axis and a distinct value on the other. The main objective is to demonstrate the relationship between the two axes.

The graph above visualises the numerical facts of the Covid-\(19\) tests in India so that they can be easily understood.

What are the Types of Bar Graphs?

A bar chart can be classified into two types, viz: horizontal and vertical bar graphs.

(i) Horizontal bar graph – Horizontal bar graphs represent the information horizontally. It is a graph whose bars (or rectangular strips) are represented horizontally. The types of data are shown on the vertical axis, and the value of data is visualized on the horizontal axis. The length of each rectangular strip is equal to the value corresponding to the type of data, and all bars go from the left to right direction on the coordinate axes.

(ii) Vertical bar graph – Vertical bar graphs represent the information vertically. It is a graph whose bars (or rectangular strips) are represented vertically. The types of data are shown on the horizontal axis and the value of data is shown on the vertical axis. The length of each rectangular strip is equal to the value corresponding to the type of data, and all bars go up from the bottom on the coordinate axes.

Bar Graphs Examples

Here is an example of a bar graph:

The above bar graph represents the number of students on the horizontal axis and colours on the vertical axis. This is a vertical bar graph since the bars are represented from downwards to upwards. The most favourite colour is Blue which \(20\) students like. And the least favourite colour is Yellow which is liked by only \(5\) students.

Properties of Bar Graphs

The properties of bar graphs are listed below:

1. The bar graphs can be represented either horizontally or vertically.
2. The width of the bar should be uniform and equally spaced.
3. All the bar graphs must have a title, label, and scale.
4. The length of the bar corresponds to the value of the given data.
5. It must start with a frequency of \(0\).

Uses of Bar Graphs

Bar graphs are helpful for comparing the classes or groups of data. They are also used to show a picture of the collected data. When we try to measure the change over time, bar graphs are considered the best when larger changes are made. Bar graphs can be arranged from highest to the lowest values. This arrangement is called Pareto Chart.

Difference Between Bar Graphs and Histograms

The histogram or frequency histogram is a graphical representation of data in rectangles with class intervals as bases and heights proportional to corresponding frequencies such that there is no gap between any two successive rectangles. In contrast, the bar graph is a graphical representation of data in bars (or rectangular strip) of uniform width such that distinct data categories can be compared easily. There is equal space between two bars.

A histogram is used for the frequency distribution of non-discrete variables, while a bar graph is used for the comparison of discrete variables. In the histogram, the blocks cannot be rearranged, whereas, in bar graphs, the bars can be rearranged from highest to the lowest value.

Advantages and Disadvantages of Bar Graphs

Bar graphs are used with numerical or categorical data.	It shows only the frequencies of the elements of a data set.
It displays each category of data in a frequency distribution.	It fails to reveal key assumptions, causes, effects, or patterns.
Large data can be easily summarized in visual form.	An additional explanation with bar graph is required.
It displays relative numbers of multiple categories.	It is a manual graphical procedure, so it is difficult to maintain a large project.
Large data set in the visual form helps us to clarify trends better than tables.
Estimates key values at a glance.
Display close numbers or proportions outline.

Summary

In this article, we have discussed the bar graphs, their definition, types o, uses, properties, their advantages and disadvantages, the difference between the bar graphs and histograms. We have also seen that two or more data sets can be compared using double bar graphs.

The data category can be displayed on one axis, and the corresponding values can be displayed on the other. The learning outcome of this article is that one can easily display the data in the form of bar graphs and able to compare the sets of data between different categories.

Solved Examples – Bar Graphs

Q.1. The following bar graph shows the sale of shirts in a readymade shop from Monday to Saturday.

How many shirts were sold on Thursday?

Ans: Here in the bar graph, the number of shirts sold on Thursday is \(35\) units.

Q.2. The following bar graph shows the marks obtained by Ajay in a half-yearly examination in different subjects.

In which subject has he scored minimum marks?

Ans: Here in the bar graph, the minimum mark is \(40\) for Social Studies.
Therefore, Ajay has scored minimum marks in Social Studies

Q.3. The following bar graph shows the marks obtained by Madhu in the Annual examination in different subjects.

Write the name of the subjects and marks obtained in each of them.

Ans: A bar graph is a pictorial representation of data in the form of vertical or horizontal bars of uniform width. They can be drawn with equal spacing between them on the horizontal axis (say, the \(X\)-axis), representing the variable. The values of the variable are shown on the vertical axis (say, the \(Y\)-axis), and the heights of the bars depend on the values of the variable.
Hence, the subjects and marks obtained are given below.

Subjects	Marks
Hindi	\(80\)
English	\(60\)
Mathematics	\(70\)
Science	\(50\)
Social Studies	\(40\)

Q.4. The bar graph given below shows the amount of wheat purchased by the state government during the year \(1998-2002\).
In which year the wheat production was minimum?

Ans: It is clear that, in \(1998\), the production of wheat was minimum, which is \(15\).

Q.5. A survey was done in a school among \(120\) students to find the activity they preferred to do in their time.

Preferred activity	Number of students
Playing	\(45\)
Reading storybooks	\(30\)
Watching TV	\(20\)
Listening to music	\(10\)
Painting	\(15\)

Draw a bar graph of the above data by considering the scale of \(1\) unit length \(=5\) students. Which activity is preferred by most of the students other than playing?

Ans: A bar graph is a pictorial representation of data in the form of vertical or horizontal bars of uniform width. They can be drawn with equal spacing between them on the horizontal axis (say, the \(X\)-axis), representing the variable. The values of the variable are shown on the vertical axis (say, the \(Y\)-axis) and the heights of the bars depend on the values of the variable.

Hence, reading storybooks is preferred by most of the students other than playing.

Frequently Asked Questions (FAQs) – Bar Graphs

Q.1: What is meant by bar graph?
Ans: A bar graph is a pictorial representation of data in the form of vertical or horizontal bars of uniform width.  

Q.2: What are bar graphs used for?
Ans: A bar graph is used to display the comparison between two or more categories. It consists of two or more parallel vertical (or horizontal) rectangles.

Q.3: What are the different types of bar graphs?
Ans: A bar chart can be classified into two types horizontal and vertical bar graphs.

Q.4: What is a bar graph explain with an example?
Ans: In a bar graph, bars of uniform width is drawn with various heights. The height of a bar represents the frequency of the corresponding observation.
For example: If you want to record the expenditure of your family on different heads like Food, Education, Clothing, House rent, etc. in a month then take the different heads of expenditure along the \(x\)-axis and the corresponding expenditure along the \(y\)-axis.
Draw the bars of the same width having their heights proportional to the expenditure in corresponding heads, keeping the same space between two consecutive bars.

Q.5: What are the 6 types of graphs or charts?
Ans: The most popular types of graphs are line graphs, bar graphs, pie charts, scatter plots, bubble charts, and histograms. 

Q.6: What are the advantages of bar graphs?
Ans: The main advantages of bar graphs are:

1. Bar graphs can be used with numerical or categorical data.
2. It presents each category of data in a frequency distribution.
3. Large data can be easily summarized in visual form.
4. It presents relative numbers of multiple categories.
5. Large data set in the visual form helps us to clarify trends better than tables.
6. It presents close numbers or proportions outline.
7. Bar graphs estimate key values at a glance.

Q.7: What do bar graphs represent?
Ans: A bar graph is a graph that depicts data using rectangular bars or columns (called bins) that reflect the total number of observations in a category.