Choose and critique statistical diagrams
Choose a suitable named display, compare samples fairly, and repair misleading scales or inconsistent symbol keys using the verified data.
Section 6.1 · Graphical representation of data
Exam scope and assessment notes
The first six lessons are shared Foundation work inherited by Higher; the last four are additional Higher histograms and cumulative-frequency work. Construct actual labelled diagrams with their scales, units and keys. Unequal continuous intervals need frequency density and area; partial-class and straight-guide readings are estimates, and a flat inverse can be an interval. Numerical agreement does not award marks or establish mastery; written explanations need human review. Statistical measures and probability remain separate. Linear November 2026/June 2027 entries and regional-centre eligibility differ from modular awards. Publisher map/contents are navigation only: F6.1Aii is a modular subpart, not the whole linear F6.1A row. Book1 Handling Data3 map398–428 differs from proof397/summary426/next428; Book2 Handling Data6 map208–222 differs from proof207/summary221/next222. Relevant chapter and Hub bodies remain unavailable; specialist and formal-assessment approval remain pending.
Before you begin
- Read and construct Foundation bar charts, pie charts and keyed pictograms.
- Calculate a fraction or percentage of a stated total.
- Distinguish source observations from a proposed display of them.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which comparison fairly tests whether an activity has a larger share in two unequal-sized samples?
What you will learn
- Choose a bar, pie or pictogram display for the question and data.
- Compare proportions when sample totals differ and distinguish count ratios from visual lengths.
- Explain and construct a corrected display while preserving verified observations.
Survey A has 40 responses: 10 choose cycling and 30 another option. Survey B has 60 responses: 24 choose cycling and 36 another option. Compare both the cycling counts and their proportions. Construct equally scaled percentage bars or complete labelled pie charts, state the percentage-point difference and explain why raw counts alone are insufficient for a share comparison.
Choose your representation, enter its actual categories, counts, geometry and labels, and explicitly record it. No table margin, scale, missing sector, density, cumulative point or reading trace is filled for you.
Original supplied data
Only literal data are supplied. A missing entry is displayed as not supplied; requested totals, frequencies, angles, density calibration, cumulative constructions and read-off traces are not generated on this board.
All metric panels in this board share one camera and equal Cartesian drawing units. Equal full widths, heights and pie radii therefore stay visibly comparable; no individual panel is independently fitted. Histogram numerical frequency density is its entered vertical calibration. Tables and tally strokes are symbolic displays.
Blank construction plane
unready actual work. No target values or construction points are supplied.
Blue is supplied geometry, amber is my actual work, purple is dirty retained work and green is a separately gated reference. Rendering never repairs a wrong count, overlap, radius, calibration, cumulative decrease or read-off elbow. Tool coordinates are bounded to±1000000; finite unsupported portions are not silently clamped. Up to1000 explicit pictogram pieces and100 tally bundles per displayed row are rendered. Screen size is not physical instrument calibration. Readiness and fixed numerical comparison do not mark reasoning, award marks, prove mastery or provide teacher/specialist/formal-assessment approval.
Observed and whole-class counts stay distinct from within-class histogram or cumulative-guide estimates. A zero-frequency plateau can give an interval of inverse readings. No median, quartile, midpoint-mean or probability teaching credit is supplied by this display.
My first sample percentage bar or complete pie
No actual representation is recorded for this action.
The board places only the coordinates you explicitly choose into the selected slot. It generates no other corner, bar, sector or reading elbow. Interval-area bounds are two measurements, not a planar point.
My quantities, conclusions and explanation
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Enter an exact fraction or finite decimal, with the precision and quantity unit explicitly requested in the question.
Explain the actual construction and its conditions. Text presence does not establish a correct argument.
These original fixed cases support self-checking. They do not mark proofs or written explanations, award marks or mastery, certify instrument accuracy, or provide specialist or formal assessment approval. Within-class histogram and cumulative-guide readings are estimates, while supplied whole-class counts remain exact. A plateau may give an interval rather than one inverse reading.
Choose the display for the question
Begin with what the reader needs to compare. A separated bar chart makes category frequencies easy to compare on one count scale. A pie chart emphasises each category’s share of a whole sample. A pictogram can communicate counts clearly when its key and part symbols fit the data. State why your choice suits the requested comparison.
A valid choice still needs the actual drawing: labelled categories, a calibrated axis or a complete circle, and a key wherever symbols or series are used. Retain zero categories and all verified frequencies. A name such as bar chart, without a correctly constructed display, does not answer a construction task.
Compare different wholes fairly
If two samples have different totals, a larger category count does not by itself mean a larger share. Divide each category count by its own sample total before comparing the fractions or percentages. When using percentage bars, make equal full bar lengths represent 100% and label the compared sections clearly.
Two equally sized pie charts can also compare proportions, with their sample totals stated separately. The count comparison and proportion comparison are both legitimate questions, but they answer different things. Explain which you are making and keep percentage-point differences distinct from percentage increases relative to a starting count.
Diagnose and repair rather than decorate
Test a visual claim against the data and its scale. On a truncated bar axis, subtract the baseline to understand the visible lengths, then compare the original counts before accepting a claim about doubling. A zero-based redraw can show the size of the count difference without the same visual exaggeration.
For a suspect pictogram, multiply the displayed icon amount by its declared key and compare the result with the verified count. If these disagree, name the inconsistent row and redraw from the verified data with a suitable key. Rounding an impossible fractional individual does not restore the original evidence; explain the mismatch and the corrected construction.
Sources for this lesson
- Pearson Mathematics A linear specification · Issue 2 · Foundation printed 24 / physical 30; Higher printed 39 / physical 45; inheritance printed 27 / physical 33
- Pearson 2026/2027 entry manual · centre regions physical 3; Mathematics A physical 25
- Pearson second-edition modular book/Hub map · literal navigation only · physical 7, 9, 11
Pause and explain
A whole icon represents 6 people. A proposed row shows 2.5 icons, but the verified count is 16. What is the justified conclusion?
Worked example
Survey A has 40 responses: 10 choose cycling and 30 another option. Survey B has 60 responses: 24 choose cycling and 36 another option. Compare both the cycling counts and their proportions. Construct equally scaled percentage bars or complete labelled pie charts, state the percentage-point difference and explain why raw counts alone are insufficient for a share comparison.
Show the worked solution
- Keep the sample totals separate: A has 10+30=40 and B has 24+36=60. The cycling counts are 10 and 24, so B has more cycling responses as a count.
- Divide by each sample’s own total: A gives 10/40=1/4=25%, while B gives 24/60=2/5=40%. The difference is 40−25=15 percentage points, not a 15% relative increase.
- Draw two equal-length bars each representing 100%, with cycling sections of 25% and 40% and other-option sections of 75% and 60%. Alternatively draw complete equal-radius pie charts: A has cycling 90° and other 270°; B has cycling 144° and other 216°. Label the key and sample totals.
- The proportion comparison uses the same whole-share scale for both samples. B is greater in both count and share here, but the conclusion about share follows from the two fractions, not from 24 being greater than 10 alone.
Answer Totals A=40 and B=60; cycling counts 10 and 24; proportions 1/4=25% and 2/5=40%, a 15-percentage-point difference. Construct equal 100% bars, or full pie charts with cycling angles 90° and 144° and remaining angles 270° and 216°. B has the greater share as well as the larger count.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A published bar chart records 96 and 104 completed jobs but starts its vertical axis at 90. Draw the two actual bars under that labelled scale and calculate their displayed lengths. Test the claim that the second count is more than twice the first. Redraw the same counts from zero, and give the actual difference, count ratio and percentage increase from the first count.
Give me a hint
First identify whether the question compares counts, shares or a proposed drawing; preserve the verified data during any repair.
Compare my reasoning
- Above the displayed baseline 90, the lengths are 96−90=6 and 104−90=14. Their visible-length ratio is 14/6=7/3, which exceeds 2, so the shortened picture can suggest more than doubling.
- Use the original counts to test the claim: 104/96=13/12, which is less than 2; equivalently 104<2×96=192. The more-than-twice claim is false.
- The count difference is 104−96=8 jobs. Relative to the first count, the percentage increase is (8/96)×100%=25/3%=8⅓%. Keep that denominator 96, not the displayed length 6.
- Draw separated equal-width bars at heights 96 and 104 from a zero baseline, with the job-count axis calibrated consistently and both category labels retained. The redraw changes their visual lengths while preserving the verified counts.
Displayed lengths are 6 and 14, with apparent ratio 7/3. Actual ratio 104/96=13/12, difference 8 jobs and percentage increase 25/3%=8⅓%; the count has not more than doubled. The corrected zero-based chart retains tops 96 and 104.
Look for these in your work
- Construct the requested corrected or chosen labelled display with a consistent key or scale.
- Use the appropriate count, total, fraction, ratio or baseline calculation.
- Explain why the proposed claim or display is justified or misleading without altering verified observations.
Verified counts for categories A, B and C are 10, 18 and 5 whole individuals. A proposed pictogram uses one whole icon for 5 individuals and shows 2, 3.5 and 1 icons respectively. Identify the inconsistent row and its implied count. Redraw all rows using one whole icon for 2 individuals, retaining exact whole and half icons. Check the total and explain why rounding cannot repair the original discrepancy.
Give me a hint
First identify whether the question compares counts, shares or a proposed drawing; preserve the verified data during any repair.
Compare my reasoning
- Read the proposed chart under its own key: A gives 2×5=10; B gives 3.5×5=17.5=35/2; C gives 1×5=5. Row B disagrees with the verified count 18.
- Use the verified counts, not the faulty display, for the redraw. Dividing by the new key 2 gives A=5 icons, B=9 icons and C=5/2=2.5 icons.
- Draw consistent whole icons and a genuine half for C, with all category labels and the explicit key one whole icon = 2 individuals. The reconstructed counts total 10+18+5=33.
- The original row represents exactly 17.5 under key 5; rounding it to 18 changes the represented value rather than making the icon row correct. The verified whole-person data require a corrected drawing.
B is inconsistent: the proposed implied counts are 10, 35/2 and 5. Under the new key 2, draw 5, 9 and 5/2 icons for A, B and C; total 33 individuals. A half new icon represents one individual. Do not round the faulty original row to conceal its mismatch.
Look for these in your work
- Construct the requested corrected or chosen labelled display with a consistent key or scale.
- Use the appropriate count, total, fraction, ratio or baseline calculation.
- Explain why the proposed claim or display is justified or misleading without altering verified observations.
A library records the number of books borrowed by 30 visitors. Values 0, 1, 2 and 3 books have frequencies 6, 11, 8 and 5. Choose and construct a suitable named display to compare these discrete frequencies, keeping the zero category labelled. Also calculate all four pie-sector angles and explain the part-to-whole question answered by that alternative display.
Give me a hint
First identify whether the question compares counts, shares or a proposed drawing; preserve the verified data during any repair.
Compare my reasoning
- The values 0,1,2,3 are discrete category labels, with frequencies 6,11,8,5. Their sum is 30. Choose a separated bar chart to compare these frequencies directly, labelling Number of books and Number of visitors.
- Construct equal-width separated bars at heights 6,11,8,5 on a consistent zero-based frequency scale. The category 0 has height 6, not zero; the horizontal value and its frequency are different quantities.
- For the pie alternative, use 360°/30=12° per visitor. The sector angles are 6×12=72°, 11×12=132°, 8×12=96° and 5×12=60°; they total 360°.
- A pie chart shows each books-borrowed category as a share of the 30 visitors. Its category labels must name those book values, while the bar chart is particularly convenient for comparing the four frequencies. Neither display changes the source data.
A suitable choice is a labelled separated bar chart with category values 0, 1, 2, 3 and heights 6, 11, 8, 5. A pie chart is also valid for shares of the whole: angles 72°,132°,96°,60° in that order. The zero-books category represents 6 visitors.
Look for these in your work
- Construct the requested corrected or chosen labelled display with a consistent key or scale.
- Use the appropriate count, total, fraction, ratio or baseline calculation.
- Explain why the proposed claim or display is justified or misleading without altering verified observations.
Common mistakes
- Comparing category counts as proportions when the sample totals differ.
- Confusing a percentage-point difference with a percentage increase.
- Changing or rounding verified counts to make a proposed chart look consistent.
What can you explain now?
A zero-based redraw changes the apparent bar-length ratio. Should it also change the labelled source frequencies?
Compare with the explanation
No. The redraw changes the presentation while preserving the same verified frequencies.
A correction is justified by an honest scale, not by altering the original observations to fit the visual claim.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Give a reason for choosing each named Foundation display and explain how you would challenge a count, proportion or visual-length claim.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.