What this lesson teaches
I can read and choose the right maps, graphs, photographs and other visual resources.
Syllabus 8834, Fieldwork, Additional Notes on Data. Students are required to be familiar with the following types of data: Maps: contour maps, choropleth maps, isoline maps, dot maps, flow-line maps, proportional symbols maps and cartograms; Graphs: pie charts, bars, histograms, scatter graphs, radar charts, triangular graphs and line graphs; Photographs: landscape photographs, aerial photographs and satellite images; Others: tables, schematic diagrams, illustrations and cartoons.
Make a guess
On a radar chart comparing two sites, Site A's shape is bigger overall. Is Site A better for older residents?
- No, not necessarily. Compare each measure first.
- Yes, because radar charts add up the scores.
- Yes. The bigger shape is the better place.
- No, because the smaller shape is better.
Show the answer
No, not necessarily. Compare each measure first.
The shape's area depends on axis order and which measures are chosen. Site B may score higher on what residents value most, such as seats or shade.
Compare each axis before judging overall, because the biggest shape is not automatically the best place.
A radar chart has several axes spreading out from a centre. Plot each score on its axis and join the points to form a shape. In this example, every axis runs from 0 to 5, and higher is better.
Site A scores higher for transport and toilets. Site B scores higher for shade and seating. Overlapping shapes make this trade-off easy to see. Explain what each score means, using an agreed rule.
Keep scales and directions the same when comparing shapes. Mixing degrees Celsius with a five-point rating makes odd shapes unless values are standardised. Flipping one axis can reverse the conclusion.
The shape's area changes with axis order, scales and which measures you pick. So it is not a measure of liveability. An overall judgement needs clear priorities. Residents who need to rest may value seats more than transport.
- Radar chart
- Several axes from a centre; scores joined into a shape.
- Same scales
- Axes must use matching scales and directions.
- Area
- Not an objective overall score.
Step by step
Read the scales
Centre, outer limit, and whether high is good.
Compare each axis
Use the exact scores.
Explain priorities
Link the judgement to residents' needs.
Worked example: A careful recommendation
"B better meets the need for shaded resting places, scoring 4 for shade and seating against A's 2. But people who rely on buses may prefer A. Check residents' priorities before calling either site best."
Watch out for this
The shape's area is an objective overall score.
Area depends on axis order, scales and choice of measures.
Check your understanding
What must be checked before overlaying two radar charts?
- That the two shapes use colours that are easy to tell apart.
- That axes, units, scale directions and scoring match.
- That both shapes have about the same area.
Show the answer
That axes, units, scale directions and scoring match.
Yes. Otherwise the shapes cannot be compared.