What is a bar graph?

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This guide explains what bar charts are and outlines the different ways in which they can be used to present data. It also provides some design tips to ensure that when you use bar charts to present data they are clear and easy to interpret.

Other useful guides:  Histograms, Pie charts, Presenting numerical data

What is a bar chart?

Bar charts are a type of graph that are used to display and compare the number, frequency or other measure (e.g. mean) for different discrete categories of data. In the example below, which shows the percentage of the British population who attended different types of cultural events during 1999-2000, the types of event are the discrete categories of data.

Bar charts are one of the most commonly used types of graph because they are simple to create and very easy to interpret. They are also a flexible chart type and there are several variations of the standard bar chart including horizontal bar charts, grouped or component charts, and stacked bar charts.

What Is a Bar Graph?

The chart is constructed such that the lengths of the different bars are proportional to the size of the category they represent. The x-axis represents the different categories and so has no scale. In order to emphasise the fact that the categories are discrete, a gap is left between the bars on the x-axis. The y-axis does have a scale and this indicates the units of measurement.   

What types of data can be displayed using a bar chart?

Bar charts are useful for displaying data that are classified into nominal or ordinal categories.

Nominal data are categorised according to descriptive or qualitative information such as county of birth, or subject studied at university.

Ordinal data are similar but the different categories can also be ranked, for example in a survey people may be asked to say whether they thought something was very poor, poor, fair, good or very good.

With nominal data, arranging the categories so that the bars grade sequentially from the largest category to the smallest category helps the reader to interpret the data.

However, this is not appropriate for ordinal data because the categories already have an obvious sequence.

Bar chars are also useful for displaying data that include categories with negative values, because it is possible to position the bars below and above the x-axis.

What Is a Bar Graph?

Different types of bar charts

Horizontal bar charts

Bar charts are normally drawn so that the bars are vertical which means that the taller the bar, the larger the category. However, it is also possible to draw bar charts so that the bars are horizontal which means that the longer the bar, the larger the category.

This is a particularly effective way of presenting data when the different categories have long titles that would be difficult to include below a vertical bar, or when there are a large number of different categories and there is insufficient space to fit all the columns required for a vertical bar chart across the page.

What Is a Bar Graph?

Note, that in Excel a chart in which the bars are presented vertically is referred to as a column chart, whilst a chart with horizontal bars is called a bar chart.

Grouped bar charts

Grouped bar charts are a way of showing information about different sub-groups of the main categories. In the example below, a grouped bar chart is used to show the different schemes (sub-groups) by which different categories of household materials are recycled.

A separate bar represents each of the sub-groups (e.g. civic amenity sites) and these are usually coloured or shaded differently to distinguish between them. In such cases, a legend or key is usually provided to indicate what sub-group each of the shadings/colours represent. The legend can be placed in the plot area or may be located below the chart.

Grouped bar charts can be used

to show several sub-groups of each category but care needs to be taken to ensure that the chart does not contain too much information making it complicated to read and interpret. Grouped bar charts can be drawn as both horizontal or vertical charts depending upon the nature of the data to be presented.

What Is a Bar Graph?

Stacked bar charts

Stacked bar chars are similar to grouped bar charts in that they are used to display information about the sub-groups that make up the different categories.

In stacked bar charts the bars representing the sub-groups are placed on top of each other to make a single column, or side by side to make a single bar.

The overall height or length of the bar shows the total size of the category whilst different colours or shadings are used to indicate the relative contribution of the different sub-groups.

Example of a stacked bar chart.

What Is a Bar Graph?

Stacked bar charts can also be used to show the percentage contribution different sub-groups contribute to each separate category. In this case the bars representing the individual categories are all the same size. The information could also be presented in a series of pie charts.

What Is a Bar Graph?

Where next?

This guide has outlined the various way in which bar charts can be used to present data and has also provided design and presentation advice.

Information about other graph and chart types and any specific design issues related to them can be found in the companion study guides: Histograms and Pie charts.

The study guide Presenting numerical data provides guidance on when to use graphs to present information and compares the uses of different graph and chart types.

Bar Graph – Definition, Types, Uses, Example Questions

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:

  • Definition
  • Types
  • Examples
  • Uses
  • Questions

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.

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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 Is a Bar Graph?

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

What Is a Bar Graph?

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

What Is a Bar Graph?

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

What Is a 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

Bar Graphs

What Is a Bar Graph?

Example 1: A survey of students' favorite after-school activities was conducted at a school. The table below shows the results of this survey.

Students' Favorite After-School Activities
Activity Number of Students
Play Sports 45
Talk on Phone 53
Visit With Friends 99
Earn Money 44
Chat Online 66
School Clubs 22
Watch TV 37

Note that since the data in this table is not changing over time, a line graph would not be a good way to visually display this data. Each quantity listed in the table corresponds to a particular category. Accordingly, the data from the table above has been displayed in the bar graph below.

What Is a Bar Graph?

bar graph is useful for comparing facts. The bars provide a visual display for comparing quantities in different categories. Bar graphs help us to see relationships quickly. Another name for a bar graph is a bar chart. Each part of a bar graph has a purpose.

title The title tells us what the graph is about.
labels The labels tell us what kinds of facts are listed.
bars The bars show the facts.
grid lines Grid lines are used to create the scale.
categories Each bar shows a quantity for a particular category.

Now that we have identified the parts of a bar graph, we can answer some questions about the graph in Example 1.

What Is a Bar Graph?

QUESTION ANSWER
1. What is the title of this bar graph?  Students' Favorite After-School Activities
2. What is the range of values on the (horizontal) scale? 0 to 100
3. How many categories are in the graph?  7
4.

Bar Graph: Definition, Types & Examples – Video & Lesson Transcript | Study.com

A bar graph is a chart that uses bars to show comparisons between categories of data. The bars can be either horizontal or vertical. Bar graphs with vertical bars are sometimes called vertical bar graphs. A bar graph will have two axes.

One axis will describe the types of categories being compared, and the other will have numerical values that represent the values of the data. It does not matter which axis is which, but it will determine what bar graph is shown.

If the descriptions are on the horizontal axis, the bars will be oriented vertically, and if the values are along the horizontal axis, the bars will be oriented horizontally.

Types of Bar Graphs

There are many different types of bar graphs. They are not always interchangeable. Each type will work best with a different type of comparison. The comparison you want to make will help determine which type of bar graph to use. First we'll discuss some simple bar graphs.

A simple vertical bar graph is best when you have to compare between two or more independent variables. Each variable will relate to a fixed value. The values are positive and therefore, can be fixed to the horizontal value.

Vertical bar graph

What Is a Bar Graph?

If your data has negative and positive values but is still a comparison between two or more fixed independent variables, it is best suited for a horizontal bar graph. The vertical axis can be oriented in the middle of the horizontal axis, allowing for negative and positive values to be represented.

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Horizontal bar graph

What Is a Bar Graph?

A range bar graph

Bar Graph – Definition with Examples

A bar graph can be defined as a chart or a graphical representation of data, quantities or numbers using bars or strips.

Bar graphs are used to compare and contrast numbers, frequencies or other measures of distinct categories of data.

Let’s represent the data given below using a bar graph. We can begin by counting each of the supplies and putting the data in a table.

What Is a Bar Graph?

Now, this bar graph below shows the different types and number of school supplies used by students. The more the height of the bar, the more is the number of the supply or item used. 

What Is a Bar Graph?

  Fun Facts

  • The bars of a bar graph can be represented both vertically and horizontally. 
  • The number of lions the number of its giraffes.
  • The number of men and women in a school staff, 
  • The number of words written in each paragraph,
  • All this data can be represented in a bar graph.

Instead of handing out worksheets or playing games around colouring bar graphs, give your child a chart paper and supplies such as a ruler, pencil and crayons. Ask them to represent the average population of 7 countries or the average number of 6-7 of their favourite animals in the world. Help them in sourcing the statistics. Ask them to mark the title, axis, scale and label the graph well. Also, help them in deciding the scale of the graph.

Bar Graph Definition and Examples

A bar graph is a chart that plots data using rectangular bars or columns (called bins) that represent the total amount of observations in the data for that category. Bar charts can be displayed with vertical columns, horizontal bars, comparative bars (multiple bars to show a comparison between values), or stacked bars (bars contain multiple types of information).

Bar graphs are commonly used in financial analysis for displaying data. A stock volume chart is a commonly used type of vertical bar graph.

 TradingView

  • Bar graphs can be created to show data in multiple, highly visual ways.
  • Bar graphs have an x- and y-axis and can be used to showcase one, two, or many categories of data.
  • Data is presented via vertical or horizontal columns.
  • The columns can contain multiple labeled variables (or just one), or they can be grouped together (or not) for comparative purposes.

The purpose of a bar graph is to convey relational information quickly as the bars display the quantity for a particular category. The vertical axis of the bar graph is called the y-axis, while the bottom of a bar graph is called the x-axis.

When interpreting a bar graph, the length of the bars/columns determines the value as described on the y-axis.

The x-axis could be any variable, such as time, or the category that is being measured, such as earnings per share (EPS), revenue, and/or cash flow.

A typical bar graph has a label or title, x-axis, y-axis, scales or increments for the axis, and bars. Some graphs may also have a legend that specifies what various colors represent, such as in a stacked bar graph.

Bar graphs are ideal for comparing two or more values, or values over time. Data is displayed either horizontally or vertically. Single bar graphs are used to convey discrete values of an item within a category.

For instance, a bar graph could display the number of males with a certain trait for specific ages. The discrete value, or the number of instances in which an individual has a certain trait, is displayed by varying the length of the bar.

More instances mean a longer bar, and fewer instances mean a shorter bar. In this example, a different bar is established for each age or age group.

In technical analysis, a volume chart shows how much volume there was on each particular day. The x-axis shows days, while a bar extending up from that day shows how much volume there was per the y-axis.

When a graph has a well-defined zero point and the data set has both positive and negative values in relation to this point, bars can still be displayed. Bars above the zero line typically represent positive values (check the scale) while bars below the zero line typically show negative values.

Data can be displayed horizontally or vertically. To switch the orientation, the x- and y-axis are switched.

Grouped bar graphs, also called clustered bar graphs, represent discrete values for more than one item that share the same category. A bar graph could display the number of individuals, male and female, with a certain trait for specific ages.

The aggregate number of instances could be combined into one bar.

Alternatively, the instances could remain segregated by gender; one bar for all male instances and one bar for all females instances would be placed side by side for each age or age group.

Stacked bar graphs or composite bar graphs divide an aggregate total into parts. These parts are typically identified by utilizing different colors for each section.

In the example above, the aggregate of instances for both males and females may be combined into one bar but the bar may be divided into multiple sections represented by different colors.

Stacked bars require a legend or specific labeling to identify what the various or parts of the bar are showing.

Some forms of technical analysis utilize bar graphs. For instance, traders may employ a moving average convergence divergence (MACD) histogram, which is a popular technical indicator that illustrates the difference between the MACD line and the signal line.

The following daily chart of Apple Inc. (AAPL) shares shows three types of bar graphs.

What Is a Bar Graph?

A bar graph or a bar chart is used to represent data visually using bars of different heights or lengths. Data is graphed either horizontally or vertically, allowing viewers to compare different values and draw conclusions quickly and easily.

A typical bar graph will have a label, axis, scales, and bars, which represent measurable values such as amounts or percentages. Bar graphs are used to display all kinds of data, from quarterly sales and job growth to seasonal rainfall and crop yields.

The bars on a bar graph may be the same color, though different colors are sometimes used to distinguish between groups or categories to make the data easier to read and interpret.

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Bar graphs have a labeled x-axis (horizontal axis) and y-axis (vertical axis).

When experimental data is graphed, the independent variable is graphed on the x-axis, while the dependent variable is graphed on the y-axis.

Bar graphs take different forms depending on the type and complexity of the data they represent. They can be as simple, in some cases, as two bars, such as a graph representing the vote totals of two competing political candidates. As the information becomes more complex, so will the graph, which may even take the form of a grouped or clustered bar graph or a stacked bar graph.

Single: Single bar graphs are used to convey the discrete value of the item for each category shown on the opposing axis. An example would be a representation of the number of males in grades 4-6 for each of the years 1995 to 2010.

The actual number (discrete value) could be represented by a bar sized to scale, with the scale appearing on the X-axis. The Y-axis would display the corresponding years. The longest bar on the graph would represent the year from 1995 to 2010 in which the number of males in grades 4-6 reached its greatest value.

The shortest bar would represent the year in which the number of males in grades 4-6 reached its lowest value.

Grouped: A grouped or clustered bar graph is used to represent discrete values for more than one item that share the same category. In the single bar graph example above, only one item (the number of males in grades 4-6) is represented.

But one could very easily modify the graph by adding a second value that includes the number of females in grades 4-6. The bars representing each gender by year would be grouped together and color-coded to make it clear which bars represent the male and female values.

This grouped bar graph would then allow readers to easily compare the number of students enrolled in grades 4-6 both by year and by gender.

Stacked: Some bar graphs have each bar divided into subparts that represent the discrete values for items that constitute a portion of the whole group.

For instance, in the examples above, students in grades 4-6 are grouped together and represented by a single bar. This bar could be broken into subsections to represent the proportion of students in each grade.

Again, color coding would be needed to make the graph readable.

Bar chart

Example of a grouped bar chart.

A bar chart or bar graph is a chart or graph that presents categorical data with rectangular bars with heights or lengths proportional to the values that they represent. The bars can be plotted vertically or horizontally. A vertical bar chart is sometimes called a column chart.

A bar graph shows comparisons among discrete categories. One axis of the chart shows the specific categories being compared, and the other axis represents a measured value. Some bar graphs present bars clustered in groups of more than one, showing the values of more than one measured variable.

History

Many sources consider William Playfair (1759-1824) to have invented the bar chart and the Exports and Imports of Scotland to and from different parts for one Year from Christmas 1780 to Christmas 1781 graph from his The Commercial and Political Atlas to be the first bar chart in history. Diagrams of the velocity of a constantly accelerating object against time published in The Latitude of Forms (attributed to Jacobus de Sancto Martino or, perhaps, to Nicole Oresme)[1] about 300 years before can be interpreted as “proto bar charts”.[2][3]

Usage

Example of a vertical 3D bar chart (frequency of personal pronouns).

Bar charts have a discrete domain of categories, and are usually scaled so that all the data can fit on the chart. When there is no natural ordering of the categories being compared, bars on the chart may be arranged in any order. Bar charts arranged from highest to lowest incidence are called Pareto charts.

Bar graphs/charts provide a visual presentation of categorical data.[4] Categorical data is a grouping of data into discrete groups, such as months of the year, age group, shoe sizes, and animals. These categories are usually qualitative. In a column bar chart, the categories appear along the horizontal axis; the height of the bar corresponds to the value of each category.

Grouped and stacked

Bar graphs can also be used for more complex comparisons of data with grouped bar charts and stacked bar charts.[4] In a grouped bar chart, for each categorical group there are two or more bars. These bars are color-coded to represent a particular grouping.

example, a business owner with two stores might make a grouped bar chart with different colored bars to represent each store: the horizontal axis would show the months of the year and the vertical axis would show the revenue.
Alternatively, a stacked bar chart could be used.

The stacked bar chart stacks bars that represent different groups on top of each other. The height of the resulting bar shows the combined result of the groups. However, stacked bar charts are not suited to data sets where some groups have negative values.

In such cases, grouped bar chart are preferable.

Grouped bar graphs usually present the information in the same order in each grouping. Stacked bar graphs present the information in the same sequence on each bar.

See also

  • See Extension:EasyTimeline to include bar charts in Wikipedia.
  • Enhanced Metafile Format to use in office suits, as MS PowerPoint.
  • Histogram, similar appearance – for continuous data
  • Misleading graph

References

  1. ^ Clagett, Marshall (1968), Nicole Oresme and the Medieval Geometry of Qualities and Motions, Madison: Univ. of Wisconsin Press, pp. 85–99, ISBN 0-299-04880-2
  2. ^ Beniger, James R.; Robyn, Dorothy L. (1978), “Quantitative Graphics in Statistics: A Brief History”, The American Statistician, Taylor & Francis, Ltd.

    , 32 (1): 1–11, doi:10.1080/00031305.1978.10479235, JSTOR 2683467

  3. ^ Der, Geoff; Everitt, Brian S. (2014). A Handbook of Statistical Graphics Using SAS ODS. Chapman and Hall – CRC. ISBN 1-584-88784-2.
  4. ^ a b Kelley, W. M.; Donnelly, R. A. (2009) The Humongous Book of Statistics Problems.

    New York, NY: Alpha Books ISBN 1592578659

External links

Wikimedia Commons has media related to Bar charts.
  • Directory of graph software and online tools (many can handle bar charts)

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