Bar Charts & Pictograms | Mathematics for GCSE/IGCSE - Year 11 PDF Download

Bar Charts & Pictograms

What is a bar chart and what is it used for?

• A bar chart visually represents qualitative and/or discrete data such as colors of cars, shoe sizes, and names of students.
• Bar charts are ideal for situations with a small number of possible outcomes where the data is categorical (non-numerical).
• The vertical axis displays the frequency, starting at zero and increasing equally.
• The horizontal axis shows the different outcomes.
• Each bar in a bar chart represents an outcome, with the height indicating the frequency.
• All bars should have the same width, and there should be gaps between them.

• You can easily identify the mode using a bar chart. 
  • The mode represents the most common outcome in a dataset. 
  • It is depicted by the bar with the highest height.
  • For instance, in a bar chart showing shoe sizes, if size 10 has a frequency of 11, then 10 is the modal shoe size.
• Comparative bar charts are useful for comparing two or more datasets.
  • In these charts, bars for each outcome are displayed for every dataset side by side without any gaps.
  • To differentiate between bars from different datasets, colors or shading are used along with a key for clarity.

What is a pictogram and what is it used for?

• A pictogram offers an alternative to a bar chart, providing a visual representation of qualitative and/or discrete data.
  • Like bar charts, pictograms are typically employed for categorical (non-numerical) data.
• Pictograms lack axes; instead, they use symbols to denote frequency.
  • It's crucial to include a key in a pictogram indicating the frequency represented by one symbol.
  • Half and quarter symbols are commonly utilized.
• Pictograms should follow similar conventions as bar charts to ensure ease of reading and interpretation.
  • All symbols should maintain uniform size and shape.
  • Symbols should be arranged in a manner that facilitates the clear observation of the highest frequency (the mode) and other relevant features.
• Here's what a pictogram depicting the shoe sizes of class 11A would resemble.