Bar Graph

Bar graphs are the pictorial representation of data (generally grouped), in the form of vertical or horizontal rectangular bars, where the length of bars are proportional to the measure of data. They are also known as bar charts. Bar graphs are one of the means of data handling, in statistics.

The collection, presentation, analysis, organization and interpretation of observations or data is known as statistics. The statistical data can be represented by various methods such as tables, bar graphs, pie charts, histograms, frequency polygons etc. In the upcoming discussion, the collection of data through a bar graph is discussed.

Table of Contents:

Bar Graph Definition

The pictorial representation of a grouped data, in the form of vertical or horizontal rectangular bars, where the lengths of the bars are equivalent to the measure of data, are known as bar graphs or bar charts.

The bars drawn are of uniform width and the variable quantity is represented on one of the axes. Also, the measure of the variable is depicted on the other axes. The heights or the lengths of the bars denote the value of the variable and these graphs are also used to compare certain quantities. The frequency distribution tables can be easily represented using bar charts which simplify the calculations and understanding of data.

What are Bar Graphs

Types of Bar Charts

The bar graphs can be vertical or horizontal. The primary feature of any bar graph is its length or height. If the length of the bar graph is more, then the values are greater of any given data.

Bar graphs normally show categorical and numeric variables arranged in class intervals. They consist of an axis and a series of labelled horizontal or vertical bars. The bars represent frequencies of distinctive values of a variable or commonly the distinct values themselves. The number or values on the x-axis of a bar graph or the y-axis of a column graph are called the scale.

The types of bar charts are as follows:

  1. Vertical bar chart
  2. Horizontal bar chart
  3. Range bar chart

Vertical Bar Graphs

When the grouped data are represented vertically in a graph or chart with the help of bars, where the bars denote the measure of data, such graphs are called vertical bar graphs. The data is represented along the y-axis of the graph and the height of the bars shows the values.

Horizontal Bar Graphs

When the grouped data are represented horizontally in a chart with the help of bars, then such graphs are called horizontal bar graphs, where the bars shows the measure of data. The data is depicted here along the x-axis of the graph and the length of the bars denote the values.

Bar Graph Examples

To understand the above types of bar graphs, consider the following examples:

Example 1: In a firm of 400 employees, the percentage of monthly salary saved by each employee is given in the following table. Represent it through a bar graph.

Savings (in percentage) Number of Employees(Frequency)
20 105
30 199
40 29
50 73
Total 400

Solution: The given data can be represented as

Bar graph - Vertical

This can be also represented using a horizontal bar graph as follows:

Bar Graph - Horizontal

Example 2: A cosmetic company manufactures 4 different shades of lipstick. The sale for 6 months is shown in the table. Represent it using bar charts.

Month Sales (in units)
Shade 1 Shade 2 Shade 3 Shade 4
January 4500 1600 4400 3245
February 2870 5645 5675 6754
March 3985 8900 9768 7786
April 6855 8976 9008 8965
May 3200 5678 5643 7865
June 3456 4555 2233 6547

Solution: The graph given below depicts the following data

Bar Graph

Example 3: The variation of temperature in a region during a year is given as follows. Depict it through graph (bar).

Month Temperature
January -6°C
February -3.5°C
March -2.7°C
April 4°C
May 6°C
June 12°C
July 15°C
August 8°C
September 7.9°C
October 6.4°C
November 3.1°C
December -2.5°C<

Solution: As the temperature in the given table has negative values, it is more convenient to represent such data through a horizontal bar graph.

Bar Graph Example

Uses of Bar Graphs

Bar graphs are used to match things between different groups or to trace changes over time. Yet, when trying to estimate change over time, bar graphs are most suitable when the changes are bigger.

Bar charts possess a discrete domain of divisions and are normally scaled so that all the data can fit on the graph. When there is no regular order of the divisions being matched, bars on the chart may be organised in any order. Bar charts organised from the highest to the lowest number are called Pareto charts.

Bar Graph Question

Question: A school conducted a survey to know the favourite sports of the students. The table below shows the results of this survey.

Name of the Sport Total Number of Students
Cricket 45
Football 53
Basketball 99
Volleyball 44
Chess 66
Table Tennis 22
Badminton 37

From this data,

1. Draw a graph representing the sports and the total number of students.

2. Calculate the range of the graph.

3. Which sport is the most preferred one?

4. Which two sports are almost equally preferred?

5. List the sports in ascending order.

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