Bar Graphs and Tally Charts

Bar Graph Definition

• A bar graph is a visual representation of data, displaying information in a clear way.
• It consists of bars that run either vertically from the x-axis or horizontally from the y-axis, sorted into categories based on the data collected.
• The length of each bar represents a number, and the order of the categories does not matter.

Types of Bar Graphs

• Simple bar graphs:
  • Show data in clearly defined categories.
  • Examples: vertical bar graphs and horizontal bar graphs.
• Vertical bar graphs:
  • Display data in columns that extend upward from the x-axis.
  • Very commonly used type of bar graph.
• Horizontal bar graphs:
  • Similar to vertical bar graphs, but with categories on the y-axis and columns extending from left to right.
  • Scale is displayed on the x-axis.
• Range bar graphs:
  • Display data with bars that do not necessarily start at zero, showing a range of data.
  • Can be displayed vertically or horizontally.
• Histograms:
  • Show numerical data, instead of categories.
  • Display data based on frequency, or how often something occurs.
  • Bars are often close together without space in between.
• Grouped bar graphs:
  • Display multiple sets of data to compare them.
  • Bars can be shown in either a vertical or horizontal format.
  • Often includes a key describing the colors of the bars.
• Composite bar graphs:
  • Show different sets of data on single horizontal or vertical bars.
  • Sections of the bars are colored differently to reflect a breakdown of the data.
  • A key explains the color-coding system used on the bars.

Using Types of Bar Graphs

• Different types of bar graphs are suitable for different scenarios, such as:
  • Basic bar graph for showing grades received by students.
  • Range bar graph for tracking sunlight hours over a month.
  • Grouped bar graph for comparing sales of different treats on different days.

How to Create a Bar Graph

• Basic steps to create a bar graph:
  • Draw the x- and y-axes.
  • Decide which axis will display categorical data and which will display numerical data.
  • Label each axis.
  • Determine the scale and range of the numerical axis and distribute the values along the axis.
  • Draw a corresponding bar for each category.