National 5GeographySQARevision NotesGeographical SkillsGraphical skillsGraphs & Diagrams

Graphs & Diagrams (SQA National 5 Geography): Revision Note

Exam code: X833 75

Bridgette Barrett

Last updated

Interpreting and presenting graphs

Examiner Tips and Tricks

Graphs will be part of the exam, and you will be expected to describe and interpret them. You will also use graphs in your fieldwork assignment. The information below outlines the strengths and limitations of each type of graph so you can judge where best to use them.

Types of data

  • Continuous data is numerical data that can take any value within a given range, e.g. heights and weights

  • Discrete data is numerical data that can only take certain values, e.g. shoe size

  • Quantitative data is where the results can be expressed using numerical values

  • Qualitative data is where the results can’t be expressed as numbers, e.g. opinions

Line graph

  • One of the simplest ways to display continuous data

  • Both axes are numerical and continuous

  • Used to show changes over time and space

Strengths

Limitations

  • Shows trends and patterns clearly

  • Quicker and easier to construct than a bar graph

  • Easy to interpret 

  • Anomalies are easy to identify

  • Does not show causes or effects

  • Can be misleading if the scales on the axis are altered

  • If there are multiple lines on a graph, it can be confusing

  • Often requires additional information to be useful

Example

  • A river cross-section is a particular form of line graph because it is not continuous data, but the plots can be joined to show the shape of the river channel

Line graph depicting a river channel cross-section, showing depth in metres on the vertical axis and width in metres on the horizontal axis.
Example of a line graph

Bar chart

  • A bar chart is the simplest form of displaying data

  • Each bar is the same width but can have varying lengths

  • Each bar is drawn an equal distance apart (equidistant)

  • The data is discrete data

  • Bar graphs are useful for:

    • Comparing classes or groups of data

    • Changes over time

Strengths

Limitations

  • Summarises a large set of data 

  • Easy to interpret and construct

  • Shows trends clearly

  • Requires additional information

  • Does not show causes, effects or patterns; can be too simplistic

  • Can only be used with discrete data

Example

Bar graph showing cross-sectional area in square metres for sites 1 to 6. Values increase progressively from site 1 to site 6.
A typical bar graph

Worked Example

Study Diagram Q14A. Describe, in detail, the changes in deforestation in the Amazon.

[4 marks]

Bar chart showing Amazon deforestation from 2013 to 2023 in millions of hectares, peaking at 3.5 in 2016 and 2017, with fluctuations in other years.

Answer

Overall, deforestation has increased. [1] Between 2014 and 2016 it increased by 1.7 million hectares. [1] Whereas between 2017 and 2018 deforestation decreased by 1.4 milllion hectares. [1] It then increased again between 2013 and 2023 by 1.2 million hectares. [1]

Examiner Tips and Tricks

When describing a graph, start with the overall trend, is it:

  • Increasing

  • Decreasing

  • Fluctuating

Then look for the most significant changes. What is highest/lowest? Where/when have the biggest changes happened?

Don't forget to include figures in your answer.

Histograms

  • Histograms show continuous data

  • Always use a ruler to draw the bars

  • All bars should be the same width 

  • The top of the bar should reach the number on the side of the graph that is being represented

  • There should be no gaps; all bars should be touching

  • Ensure all axes are labelled and that the graph has a title

Strengths

Limitations

  • Large data sets can be graphed easily

  • Data can be compared

  • Can be difficult to pinpoint exact data values

  • They can only be used for numerical data

Example

Histogram showing pebble count by size. X-axis: pebble length in cm, Y-axis: number of pebbles. Peaks at 10-20 cm range, declining at higher sizes.
Example of a histogram

Compound or divided bar chart

  • The bars are subdivided to show the information, with all bars totalling 100%

  • Divided bar charts show a variety of categories

  • They can show percentages and frequencies

Strengths

Limitations

  • A large amount of data can be shown on one graph    

  • Percentages and frequencies can be displayed on divided bar charts

  • A divided bar chart can be difficult to read if there are multiple segments

  • It can be difficult to compare data sometimes

Example

Bar chart showing traffic counts at Site 1 from 8:30 to 10:30 AM. Categories: cars, buses, lorries, motorbikes, bikes. Peaks at 8:30-9:00 AM.
Example of a compound bar chart

Population pyramid

  • This is a type of histogram

  • Used to show the age-sex of a population

  • It can be used to show the structure of an area/country

  • Patterns are easy to identify

Strengths

Limitations

  • Easy to compare age and sex data

  • Easy to read and annotate

  • Can take a long time to construct

  • Detail can be lost in the data (figures just show a cohort); additional annotations may be necessary

Example

Population pyramid chart showing age distribution by gender. Males in blue on the left, females in red on the right, both with population in millions.
Example of a population pyramid

Worked Example

Study Diagram Q9.

Give reasons for the differences between the population structures of Italy and Mozambique.

You should refer to both birth rates and death rates in your answer.

[6 marks]

Population pyramids for Italy and Mozambique in 2022. Italy shows an older population structure, while Mozambique displays a youthful population.

Answer

Birth rates are higher in Mozambique, where many women lack health education [1] and there is less access to contraception. [1] Families in Mozambique may be larger as they need children to work to help support the family [1] or to care for parents in their old age because there is less access to pensions. [1] In Italy there is a longer life expectancy due to better access to health care [1] and better diets. [1]

Pie chart

  • Used to show proportions, the area of the circle segment represents the proportion

  • A pie chart can also be drawn as a proportional circle 

  • Pie charts can be located on maps to show variations at different sample sites

  • The percentage of the pie chart must add up to 100%

  • To calculate degrees of the pie chart (which totals 360°), divide the percentage by 100 and then multiply by 360

  • Each segment should be a different colour

Strengths

Limitations

  • Clearly shows the proportion of the whole

  • Easy to compare different components

  • Easy to label

  • Information can be highlighted by separating segments

  • Does not show changes over time; hard to compare two sets of data

  • Difficult to understand without clear labelling

  • Calculating the size of each section can be difficult

  • Can only be used for a small number of categories; otherwise, lots of segments become confusing

Example

Pie chart showing energy sources: 38% coal, 22% oil, 20% renewable, 15% gas, 5% nuclear; colours are blue, orange, light blue, grey, yellow.
Pie chart showing energy sources in an area

Examiner Tips and Tricks

To work out the percentage increase/decrease, work out the difference between the two numbers, divide the difference by the first number, then multiply this number by 100.

For example, the difference between 37 and 43 is 6. Then 6 / 37 x 100 = 16.21.

The percentage increase is therefore 16.21%.

Scatter graph

  • Points should not be connected

  • The best fit line can be added to show the relations

  • Used to show the relationship between two variables

    • In a river study, they are used to show the relationship between different river characteristics, such as the relationship between the width and depth of the river channel

Strengths

Limitations

  • Clearly shows data correlation

  • Shows the spread of data

  • Makes it easy to identify anomalies and outliers

  • Data points cannot be labelled

  • Too many data points can make it difficult to read

  • Can only show the relationship between two sets of data

Example

Scattergraph showing the relationship between river width (0-50m) and depth (0-5m) with plotted data points and a trend line.
Example of a scatter graph with a trend line (aka line of best fit)

Types of correlation

  • Positive correlation

    • As one variable increases, so too does the other

    • The line of best fit goes from bottom left to top right of the graph

  • Negative correlation 

    • As one variable increases, the other decreases

    • The line of best fit goes from the top left to the bottom right of the graph

  • No correlation

    • Data points will have a scattered distribution

    • There is no relationship between the variables

Diagram showing three types of correlation: positive (upward trend), negative (downward trend), and no correlation (random scatter).
Examples showing three types of correlation

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Bridgette Barrett

Author: Bridgette Barrett

Expertise: Geography, History, Religious Studies & Environmental Studies Subject Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 30 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.