Types of graphs in geography
Graphs are a useful way to show numerical data. There are a variety of graphs that can help highlight patterns and be used to reach conclusions. Choosing the right graph is very important.
Exploring a range of graphs and their uses
Line graphs
Line graphs show how data changes over time or space. The The line that runs along the bottom of a graph. shows time or distance. A line chart could be used to show the changes in a country's employment structure over time. This graph shows that in the post-industrial era approximately 11 per cent of unemployed people work in primary industries, 31 per cent in secondary industries, 54 per cent in tertiary industries and 4 per cent work in quaternary industries. Note how the total adds up to 100 per cent.
Bar charts
Bar charts show grouped data as rectangular bars, eg the number of Someone who travels for recreation or business purposes. visiting a resort each month. Divided bar charts split up each rectangular bar to break the information down further. A divided bar chart could be used to show the age breakdown of tourists visiting a resort.
A graph which shows the age and gender structure of a population. are bar charts that show how many people of different ages are living in a place or country. Population pyramids show the bars arranged sideways, rather than upwards. The x-axis shows the number of people, the The line that runs up the side of a graph. shows their ages. The bars on the left show the number of males and the bars on the right show the number of females.
This pyramid is using absolute figures but population pyramids can also use percentage figures on the x-axis.
Bar charts and line graphs can be combined together. Climate graphs are an example of this. The x-axis shows the months of the year and there are two y-axes to show average temperature and total rainfall. The temperature is shown as a green line and the rainfall as bars.
Discrete bar graphs are required when the data to be presented is not continuous. Therefore discrete bar graphs will always have gaps (of equal distance) between them.
When reading climate graphs there are five readings which are standard:
- maximum temperature = the highest temperature recorded
- minimum temperature = the lowest temperature recorded
- range of temperature = the difference between the max and min
- total annual rainfall = total of the 12 months
- rainfall pattern = the variation throughout the year
Interpreting climate graphs
You may need to look at the information in a graph and describe the area's climate.
Look for patterns in the temperature data.
- Is the temperature the same all year round? If it is different, how many seasons does the location experience?
- Which season is the warmest? Is it warm (10 to 20°C), hot (20 to 30°C) or very hot (above 30°C)?
- Which season is the coolest? Is it mild (0 to 10°C), cold (-10 to 0°C) or very cold (below -10°C)?
- What is the range of temperature? (Subtract the minimum temperature from the maximum temperature).
Look for patterns in the rainfall data.
- Does the rainfall occur all year round?
- What is the pattern of the rainfall? Check which season(s) is/are drier or wetter than others.
- What is the total annual rainfall? Add each month's total together to get the annual total.
- Then put the rainfall and temperature information together - what does it tell you about this area?
Describe the patterns in temperature and rainfall, including how they relate to each other. You now have a description of the climate.
- Now look again at the climate graph above. What can you deduce about the climate?
Histograms
Histograms are similar to bar charts, but they show The total number of times an event occurs. rather than groups of data. A histogram could be used to show frequencies of earthquakes of each The size or severity of something. For example, an earthquake. on the The measure by which the strength of earthquakes is determined..