Representing Data: Charts and Diagrams

Visual representations make data easier to interpret. At GCSE you need to draw and interpret bar charts, dual/composite bar charts, pie charts, stem-and-leaf diagrams and pictograms.

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Key Vocabulary

Term	Definition
Bar chart	Uses bars of equal width; the height represents frequency
Dual bar chart	Two sets of bars side by side for comparison
Composite bar chart	Bars stacked on top of each other
Pie chart	A circle divided into sectors; the angle of each sector is proportional to the frequency
Stem-and-leaf diagram	Displays data using stems (leading digits) and leaves (trailing digits) in order
Pictogram	Uses symbols to represent frequencies; includes a key

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Bar Charts

Drawing a Bar Chart

• Bars must be the same width with equal gaps between them.
• The vertical axis (frequency) must be labelled and scaled evenly.
• Bars should be labelled on the horizontal axis.

Dual Bar Charts