Students asked 47 shoppers at Ambleton market where they had travelled from, to find the market's sphere of influence. Figure 1 shows their results as a desire line map, with the width of each line showing the number of shoppers.
Evaluate the desire line map as a way of presenting these results.
Model answer
The desire line map is an effective way to show the market's sphere of influence because it shows both where shoppers came from and how far they travelled. The furthest origin is Thorpe, about 5 km to the north-east, so the sphere of influence can be estimated. Making the line widths proportional to the number of shoppers means the most important origins stand out: Elmdon, with 12 shoppers, and Thorpe, with 9, show that almost half the shoppers came from the north-east. The base map also helps explain this, as both villages lie along the A614.
However, the lines are straight, so they do not show the real routes people took along roads. The lines also crowd together near the market, and with more origins they would overlap and become difficult to read. Grouping shoppers by village hides exactly where they live, and the map says nothing about how they travelled or how often they visit. The map is based on only 47 people on one day, so the sphere of influence it shows may not be typical.
Overall, the desire line map is a good choice for showing direction, distance and the number of people from each place, but it would be more useful with a table of distances and a larger sample.
Explanation
A desire line map is the standard technique for showing spheres of influence, so the best answers explain why it suits the data and use the figure (origins, distances and numbers) before weighing its limitations. A conclusion should make a clear judgement rather than just repeating the points.
![Traffic entering Hexley, 8-9 am. Map of a local area, 6 km from west to east and 4 km from south to north, with north at the top. Areas: the town centre shown pink, in the centre of the map. Lines: the A61 (main road) runs from the west edge to the centre of the map, passing through the west of the map; the A631 (main road) runs from the centre of the map to the east edge, passing through the east of the map; a secondary road runs from the centre of the map to the north edge, passing through the north of the map; a minor road runs from the centre of the map to the south edge, passing through the south of the map. Flow lines (blue arrows) show vehicles per hour: the width of each is proportional to the value (key widths: 200 and 800). Flows: flow A from the west of the map to the centre of the map: wider than the 800 key line; flow B from the east of the map to the centre of the map: between the 200 and 800 key widths; flow C from the north of the map to the centre of the map: between the 200 and 800 key widths; flow D from the south of the map to the centre of the map: narrower than the 200 key line. Letters in circles: A labels a flow line that runs from the west of the map to the centre of the map; B labels a flow line that runs from the east of the map to the centre of the map; C labels a flow line that runs from the north of the map to the centre of the map; D labels a flow line that runs from the south of the map to the centre of the map. The key (beside the map) shows: [Vehicles per hour], 200, 800, town centre, main road, secondary road, minor road. Below the map: a scale bar marked 0, 1 and 2 km and a north arrow pointing to the top.](/learn/exams/assets/img/questions/geography3/33nai12xxqf5ubra.svg)
![Where shoppers at Ambleton market came from. Map of a local area, 12 km from west to east and 10 km from south to north, with north at the top. Areas: the town centre shown pink, in the centre of the map. Lines: the A614 (main road) runs from the west edge to the east edge, passing through the centre of the map; the B1220 (secondary road) runs from the centre of the map to the north edge, passing through the north of the map. Desire lines: straight lines join "Market" (a star in the centre of the map (inside the town centre; on the A614 (main road); on the B1220 (secondary road))) to 7 places; line width shows how many people came from each place (key: 1 person, 6 people and 12 people). Origins: "Ashby" in the north-west of the map (a line between the key's 1 and 6 people widths); "Thorpe" in the north-east of the map (a line between the key's 6 and 12 people widths); "Kirkham" in the south-east of the map (a line between the key's 1 and 6 people widths); "Holme" in the south-west of the map (a line as wide as the key's 6 people line); "Ryton" in the north of the map (a line between the key's 1 and 6 people widths); "Elmdon" in the centre of the map (a line as wide as the key's 12 people line); "Westfield" in the centre of the map (a line between the key's 6 and 12 people widths). The key (beside the map) shows: [Desire line], 1 person, 6 people, 12 people, survey point, town centre, main road, secondary road. Below the map: a scale bar marked 0, 2.5 and 5 km and a north arrow pointing to the top.](/learn/exams/assets/img/questions/geography3/1xy9r4efsxn8izuu.svg)