Bar Graph

A bar graph, which is also known as a Bar Chart, is a type of graphical representation that uses rectangular bars to represent data. Bar graphs are used in statistics, business, and everyday life to compare quantities across different categories. Bar graphs can represent discrete and continuous data, making it an effective tool for data analysis.

1.0How to Draw a Bar Graph

To create an effective and clear Bar Graph, one must follow these steps: 

Step 1: Collect Data 

To start, collect the data given to you or what you wish to represent. It can represent anything from the population of a country to runs scored by a cricketer.                                                                                   

Step 2: Label Axes 

Mark the x-axis with the category you want to represent, for instance, months and products, and the y-axis with the numerical values (sales, number of items sold). 

Step 3: Choose Scale

It is an important step, as choosing the wrong scale can significantly affect the shape of the bar graph. It must be noted that the scale should be in line with the data. 

Step 4: Draw Bars

Draw a bar that extends to the value on the y-axis that represents the data for that category. The bars should be proportional to the values they represent.

2.0Bar Graph Types

Based on the various components, a Bar graph can be differentiated into many types. Some of them are: 

Simple Bar Graph (or Basic Bar Graph)

A simple bar graph shows one set of data for each category. It is one of the most common types of bar graphs and is used when you want to display straightforward comparisons.

Example: A bar graph comparing the number of books sold in different months.

Vertical Bar Graph

In a vertical bar graph, the bars are drawn vertically. The height of the bars corresponds to the values of each category.

Example: A bar graph representing the sales of different products for each month. The x-axis contains the names of the products, and the number of units sold is marked on the y-axis.

Horizontal Bar Graph

In a horizontal bar graph, the bars are drawn horizontally from the y-axis. This is quite helpful when category labels are very long and there is room for them.

Example: A bar graph displaying the population of various countries where the country names are on the y-axis and population figures are on the x-axis.

Stacked Bar Graph

In a stacked bar graph, the bar is divided into segments, with each segment representing a different portion of the total value. This is used to depict how distinct subcategories are contributing to a total.

Example: A bar graph of the total sales for various months. Here, the segments represent sales coming from different regions.

Grouped Bar Graph (or Group Bar Graph)

A grouped bar graph is used to compare multiple data sets across the same categories. It consists of multiple bars for each category, allowing for comparisons between different groups.

Example: A bar graph comparing sales data for multiple stores in each month. Each category (month) will have multiple bars representing each store's sales.

Compound Bar Graph

A compound bar graph is like a stacked bar graph, except the data is broken down in greater detail. The bars represent totals, and the segments within these bars represent parts of the total value.

Example: Graph which compares total sales across different stores where every segment of the bar represents the sales of different product categories.

Percentage Bar Graph

In a percentage bar graph, the height or length of each bar represents the percentage of the total, allowing for an easy comparison of proportions.

Example: A bar graph showing the percentage of total sales for different products in a store.

Double Bar Graph

A double bar graph uses two sets of bars for each category, often to compare two different groups side by side.

Example: A bar graph comparing the sales of two different products in each month.

Component Bar Graph

A component bar graph is a variant of the stacked bar graph in which each bar is segmented into segments representing different subcategories. It is useful to show how the components contribute to the overall total.

Example: A graph showing the total units sold, where each segment represents the sales of different types of products.

3.0Advantages of Bar Graph

• Bar graphs are simple and easy to interpret data quickly, even for people without a technical background.
• Bar graphs are very effective for comparing quantities across different categories side by side.
• This can be used for various purposes such as data comparison, displaying the trend of data over time, and proportion representation.
• Bar graphs offer a clear and effective visual representation, making it easier to spot trends, patterns, and outliers in the data.
• Bar graphs can present several data sets at the same time, especially when using grouped, stacked, or compound bar graphs.

4.0Bar Graph Example

Problem 1: The bookstore has sales data for two categories of books: Fiction and Non-Fiction. The number of books sold over four months is as follows:

Create a stacked bar graph to show the total number of books sold each month, broken down by Fiction and Non-Fiction books.

Solution:

Problem 2: Draw a double bar graph for the following data showing the sales of Product A and Product B in different years: