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Bar Charts

FoundationHigherAQAEdexcel

Learn Bar Charts for GCSE Statistics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA and Edexcel. Bar charts compare the frequencies of categories using bars of equal width with gaps between them.

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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA and Edexcel specifications. Every worksheet comes with a full mark scheme.

Foundation

WorksheetFoundation · PDFMark SchemeFoundation · PDF

Higher

WorksheetHigher · PDFMark SchemeHigher · PDF

Topic overview

A bar chart represents categorical or discrete data using bars whose heights show the frequencies.

The bars must be of equal width, and there must be gaps between them. The gaps are what distinguish a bar chart from a histogram, and drawing them touching is a frequently penalised error.

Both axes must be labelled, and the frequency axis must start at zero. Starting it partway up exaggerates the differences between bars, which is a common way of misleading with statistics — and identifying that fault in a given diagram is examined regularly.

Revision notes

Drawing a bar chart

Bars must be of equal width with gaps between them.

Both axes must be labelled, and the frequency axis must start at zero. A title helps but the axis labels carry the marks.

Bar charts versus histograms

A bar chart has gaps between the bars; a histogram does not.

Bar charts suit categorical and discrete data. Histograms are for continuous data, where the bars touch because the intervals are adjacent.

Misleading bar charts

If the frequency axis does not start at zero, small differences look much larger than they are.

Other misleading features include unequal bar widths and a non-linear scale. Identifying these faults in a given diagram is a standard exam question.

Key points

  • Bars must be of equal width.
  • There must be gaps between the bars.
  • Both axes must be labelled.
  • The frequency axis must start at zero.
  • Bar charts suit categorical and discrete data.
  • Not starting at zero exaggerates differences.

Worked examples

Example 1

A bar chart's frequency axis starts at 20 rather than 0. Explain why this is misleading. [2 marks]

Working

The bars are shortened by the same amount, so the differences between them appear proportionally much largerstate the visual effect
giving the impression that the categories differ far more than they actually doexplain why it misleads

Example 2

State two features a correctly drawn bar chart must have. [2 marks]

Working

Bars of equal width with gaps between themgive the first feature
Both axes labelled, with the frequency axis starting at zerogive the second feature

Example 3

Explain one difference between a bar chart and a histogram. [1 mark]

Working

A bar chart has gaps between the bars, whereas a histogram's bars touchstate the difference

Common mistakes

  • Drawing bars touching.

    Bar charts need gaps; only histograms have touching bars.

  • Not starting the frequency axis at zero.

    This exaggerates the differences and is misleading.

  • Using unequal bar widths.

    All bars must be the same width.

  • Forgetting axis labels.

    Both axes must be labelled to earn full marks.

Exam tips

  • Leave gaps between the bars.
  • Start the frequency axis at zero.
  • Label both axes every time.
  • Learn the misleading-axis criticism — it is asked often.

Key terms

Bar chart
A diagram using separated bars to show frequencies.
Categorical data
Data in named categories, suited to bar charts.
Misleading
Presented so as to give a false impression.
Frequency axis
The vertical axis, which must start at zero.

Related topics

Written and reviewed against the current AQA and Edexcel specifications. Spotted an error? Let us know.