Recognising Misleading Graphs (Foundation)
Recognising misleading graphs is the skill of spotting ways that a chart has been drawn to give a false or exaggerated impression of the data, such as a truncated axis, an inconsistent scale, or a misleading choice of chart type. Exam questions usually show a graph and ask you to identify and explain what makes it misleading.
Before you start
Make sure you're comfortable with these topics first:
Method
- Check whether the vertical axis starts at zero; if it starts higher up, small differences between bars look much bigger than they really are.
- Check that the scale on each axis is consistent, with equal gaps representing equal amounts, since an uneven scale distorts the pattern shown.
- Check that 3D effects, or images of different sizes, have not been used to make one category appear larger than its value shows, which is common in pictograms and 3D bar or pie charts.
- Check that a pie chart's sectors actually add up to 100% of the data and are drawn in proportion to their percentages.
- Check that axis labels, units and a title are given, since a graph without them can be interpreted in a misleading way.
- Compare what the graph looks like it shows against what the actual numbers show, and describe the specific feature causing the false impression.
Worked example
A bar chart compares the sales of two shops, A and B. The vertical axis is labelled 'Sales (pounds)' but starts at 400 instead of 0. Shop A's bar reaches 420 and Shop B's bar reaches 460. Explain why this graph could be misleading.
- Because the axis starts at 400 rather than 0, only the range from 400 upwards is shown on the chart.
- This makes Shop B's bar (460) look three times as tall as Shop A's bar (420), since the visible bar heights above the 400 starting point are 60 and 20, even though the true difference is only 40 pounds.
- A reader glancing at the chart would think Shop B massively outsold Shop A, when the real difference is only about 9.5% more sales.
- So the final answer is: the graph is misleading because the truncated, non-zero vertical axis exaggerates a small real difference between the two shops.
Practice questions
Try each question, then tap to reveal the answer.
Q1A bar chart's vertical axis runs from 0 to 10 in equal steps of 2. Is this axis likely to be misleading?Show answer
Answer: No - it starts at zero with equal, consistent steps, so it fairly represents the data.
Q2A pictogram uses one whole apple symbol to represent 10 apples sold, but one row shows a half apple symbol with no key given for partial symbols. Why could this be misleading?Show answer
Answer: Without a key explaining what the half symbol means, the reader cannot tell exactly how many apples it stands for.
Q3A pie chart is drawn showing 3 sectors that look visually equal in size, but the data is 50%, 30% and 20%. What is wrong?Show answer
Answer: The sectors have not been drawn in proportion to the percentages, so the chart misrepresents how the data is split.
Q4A line graph's horizontal (time) axis has unequal gaps between the years labelled: 2010, 2011, 2015, 2016. Why could this mislead a reader?Show answer
Answer: Equal spacing on the axis should represent equal time gaps; unequal gaps for unequal time intervals distort the trend shown.
Q5A 3D pie chart is used to show market share. Explain why 3D charts can be misleading.Show answer
Answer: The 3D perspective can make sectors at the front appear larger than they actually are relative to sectors at the back, distorting the true proportions.
Q6A newspaper bar chart showing company profit over 5 years has no vertical axis labels or scale, just bars of different heights. Explain the problem with this.Show answer
Answer: Without a labelled scale, the reader cannot tell the actual values, only a vague impression of relative size, so the bars could be drawn to exaggerate a trend.
Exam-style questions
Written in the style of a GCSE Statistics exam paper, with a full mark scheme.
A bar chart comparing rainfall in two months has a vertical axis that starts at 50mm instead of 0mm. Explain why this could give a misleading impression of the data.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
A pictogram shows the number of cars sold by a dealership over 3 months, using a picture of a car to represent 5 cars. In March, 2.5 car symbols are shown but there is no key stating what a half-symbol means, and the car symbols get physically larger for later months even though each still represents 5 cars. (a) Identify two separate features of this pictogram that could mislead a reader. (b) State what should be added to fix one of these problems.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 3 available
A line graph shows a company's yearly profit. The vertical axis jumps from 0 to 100 in a small first gap, then continues in equal steps of 10 above that, and the line rises steeply near the bottom of the axis. (a) Identify the misleading feature of this axis. (b) Explain the effect this has on how the trend appears. (c) Suggest how the graph should be redrawn to avoid this problem.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 4 available
See real GCSE Statistics past-paper questions, with official mark schemes →
Free printable worksheet
Want more practice on paper? Download the recognising misleading graphs (foundation) worksheet pack - 21 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
This topic is chapter 12 of GCSE Statistics Foundation Workbook 1, the whole course as one free printable PDF.
Next topics
Not quite what you needed?
Tell us what is missing on recognising misleading graphs (foundation), or which topic to write up next. Every request is read, and we reply to every one.
Build a full practice pack.
This topic is one of hundreds in the library - pick the ones a student needs and generate a printable PDF in minutes.