Analysis and Interpretation of Geographical Sources

Turning resources into geographical evidence

A geographical issue is a matter that needs investigation or a response, such as how to meet growing water demand. Secondary sources are information produced by other people: maps, statistics, photographs, diagrams, satellite images, published extracts and quotations can all provide evidence about an issue.

In AQA’s issue evaluation, a resource booklet is available twelve weeks before the exam. This gives you time to understand its information and connections. You receive a clean copy in the exam, rather than taking in your annotated copy. Questions use the booklet and may introduce additional resources or unfamiliar contexts.

Reading a resource involves more than finding a number. Analysis identifies patterns and relationships; interpretation explains their geographical meaning; evaluation judges how useful and convincing the evidence is. For example, identifying rising water demand is analysis. Explaining how population growth could increase demand is interpretation. Checking whether the figures are measurements or uncertain forecasts is evaluation.

Establishing what a resource actually shows

Begin with the title, location and date. Then identify the variables, categories, key and units. A figure showing total water use tells you something different from one showing water use per person. Likewise, a percentage of households with piped water is not the same as the number of households with it.

Check the geographical area covered and the time period. A national average cannot tell you exactly what happens in every town. An old photograph may help explain past conditions without showing the situation today.

Keep the issue in mind as you read. For a water-supply issue, rainfall information helps you investigate availability, while population and consumption figures help you investigate demand. Their value comes partly from how they work together.

Reading graphs and identifying a meaningful trend

Read both axes and their units, then check the key if there is more than one series. Identify the overall trend, its size, any changes in direction and any anomalies. Support your description with selected values rather than listing every point.

The following graph uses example figures. It demonstrates how to analyse resources about water supply. All values represent million litres per day. The 2030 and 2040 values are projections.

Data for Illustrative water demand and available supply

Demand rises from 80 million litres per day in 2020 to 110 million litres per day in 2040, while available supply remains at 100 million litres per day. The important relationship is therefore not simply that demand increases: by 2040, projected demand exceeds supply by 10 million litres per day. This suggests a possible future shortage if the assumptions hold and nothing changes.

The demand increase is 30 million litres per day. Dividing this increase by the original demand and multiplying by 100 gives $30 \div 80 \times 100 = 37.5\%$. This expresses the increase relative to the starting value, allowing comparison with other changes.

A possible interpretation is that a growing population could increase total water use. However, the graph does not give population figures, so this explanation would need supporting evidence. Changes in use per person could also affect demand.

On a scatter graph, examine whether two variables tend to increase together, move in opposite directions or show no clear relationship. This is correlation. A relationship between two variables does not, by itself, prove that one causes the other. Other influences may help explain the pattern.

Comparing tables and statistics

Tables let you compare categories precisely, but first check the row and column headings. Compare equivalent measures: values collected in different years or using different definitions may not be directly comparable.

Consider this fictional example of access to piped water:

Access is higher in urban areas in both places. The urban–rural gap is 30 percentage points in Area A, compared with 50 percentage points in Area B. Area B therefore has the larger gap. This is more informative than saying only that the figures are different.

A percentage-point difference is found by subtracting percentages. A percentage change measures a change relative to the original value. These answer different questions.

Summary statistics can help when a resource contains many values. The mean describes the average, the median identifies the middle ordered value, and the range shows the difference between the highest and lowest values. Averages summarise a dataset, but may conceal important variation between places or groups.

Reading spatial patterns on maps

A map shows where something occurs. Read its title and key before interpreting colours or symbols. Identify the mapped area, orientation and scale, then describe the distribution using locations and directions rather than vague phrases such as ‘over there’.

For a choropleth map, each shade represents a range. Imagine a fictional rainfall map whose key places western areas in a 1,000–1,499 mm annual rainfall band and eastern areas in a 500–749 mm band. You can conclude that the mapped western areas have higher annual rainfall. You cannot give an exact rainfall total for either area from those bands alone.

Shading also hides differences within an area. A boundary between shades does not necessarily mean rainfall changes suddenly at that boundary. Transfer this method to an authentic map by using its actual key, locations and units; the fictional example does not establish a real rainfall distribution.

Scale helps you judge distance. If a map’s scale bar shows that 2 cm represents 1 km, a straight-line separation of 6 cm represents 3 km. This is not necessarily the distance travelled along a winding road.

For a topographic map, contours help you interpret relief: closely spaced contours indicate steeper slopes, while widely spaced contours indicate gentler slopes. Spot heights provide elevations at particular points. Use these together when considering the land around a proposed development.

Interpreting images, diagrams and written material

Photographs, satellite images and sketches provide visual evidence. Separate observations from inferences. Buildings and roads are human features; rivers and vegetation are physical features. Visible buildings can establish that land is developed, but a photograph alone cannot establish residents’ incomes or opinions.

Check the view and coverage. A close-up photograph may reveal detail while leaving out surrounding land uses. Its date, season and viewpoint can affect what it shows. A sketch is selective rather than a complete record of everything present.

For a diagram, follow the labels and arrows. Determine whether they show movement, stages in a process or a proposed arrangement. A simplified diagram can explain a relationship clearly without showing the real distances or every influence involved.

For written extracts, identify the main claim and the facts used to support it. Note who produced the text, when it was written and whether it reports evidence or expresses an opinion. A quotation can establish what its speaker believes, but does not automatically establish that the belief is correct.

Judging how far the evidence supports a conclusion

Evaluate evidence in relation to the claim you want to make. Ask whether it covers the right place and period, whether its measures are clear, and what it leaves out. Being a secondary source does not automatically make information unreliable: its methods and suitability matter.

Projections require particular care. Future urban population estimates may be inaccurate because the starting population count is uncertain or because economic conditions, birth rates, death rates or migration change. ‘It is a prediction’ identifies its status; explaining which assumption could change identifies a meaningful limitation.

Bring resources together where possible. A graph might show increasing demand, a map might show the location of available supplies, and an extract might explain expected population growth. Agreement can strengthen an interpretation, while disagreement may reflect different dates, definitions or areas covered.

A strong conclusion therefore states what the evidence supports and recognises its limits. In the water example, projected demand exceeds the stated supply by 2040. That supports concern about a possible shortage, but does not establish that a shortage will definitely occur: future demand and supply could change.

Read the resource

Check title, place, date, key, units, categories and coverage. Distinguish observed values from projections.

Analyse and interpret

• Graphs: overall trend, highest and lowest values, anomalies and relationships; quote data.
• Tables: compare equivalent categories directly, including the size of differences.
• Maps: use the key, scale and locations to describe spatial patterns. Shaded bands do not give exact values.
• Images: distinguish visible features from inferred explanations.
• Text and diagrams: identify claims, supporting facts, labels and relationships.

Analysis identifies patterns; interpretation explains their geographical meaning.

Essential calculations

$$\text{Percentage change}=\frac{\text{final value}-\text{original value}}{\text{original value}}\times100$$

• Percentage-point difference: subtract the two percentages.
• Mean: total divided by number of values.
• Median: middle ordered value.
• Range: highest minus lowest.

Evaluate the evidence

Check relevance, date, coverage, methods and missing information. Correlation does not prove causation. Projections depend on starting data and assumptions. Use resources together, and qualify conclusions where evidence is limited.