Bar Charts & Pictograms (Cambridge (CIE) IGCSE Maths)

Bar Charts & Pictograms

What is a bar chart?

• A bar chart is a visual way to represent discrete data

  • Discrete data is data that can be counted 

    • This can be numerical like shoe sizes in a class

    • Or non-numerical (categorical) like colours of cars down a road

• The horizontal axis shows the different outcomes

• The vertical axis shows the frequency

• The heights of the bars show the frequency

  • Bars should be separated by gaps

  • Bars should have equal widths

• The mode is the outcome with the highest bar

• You can also get dual bar charts to compare two data sets

  • Bars are in pairs (side-by-side) for each outcome

What is a pictogram?

• A pictogram is an alternative to a bar chart

  • It is used in the same situations

• There are no axes

  • Frequency is represented by symbols

  • A key shows the value of 1 symbol

    • For example, 1 symbol represents a frequency of 2

  • Half and quarter symbols are often used

• The pictogram above shows the shoe sizes of students in a class

  • As 1 picture of a shoe represents 2 students

    • Half a shoe represents 1 student

  • The number of students with a shoe size of 7, is 3