Describing Line Graphs (5) - Making Comparisons

Observe the following simple line graph:

This graph shows the change in population in two countries from 2013 to 2021. In describing this graph it is important to describe change as in any other graph, but it is also necessary to make comparisons between the two countries.

What changes are shown by this graph? In this case we can see that the population of Sweden increased from 2013 to 2021.

Also in this graph the Sweden line is fairly smooth, so we can say that the population increased steadily.

How big was the change in Sweden's population? The population in 2013 was 9.6 million and in 2021 it was 10.4 million. So there was an increase of 0.8 million or 800,000 people.

By contrast, the population of Portugal decreased from 2013 to 2021.

This change did not happen at the same rate. The population declined steadily from 2013 to 2018, but from 2018 to 2019 it remained stable. From 2019 to 2021 the population increased slightly.

How far did Portugal's population fall? The population in 2013 was 10.46 million and in 2021 it was 10.33 million. So there was an decrease of nearly 0.13 million or 130,000 people.

There is one further contrast to point out. That is that in 2013 Portugal's population was higher than Sweden's whereas in 2021 Sweden's was slightly higher than Portugal's.

A Question of Scale

Be careful to look at the scale. Although the differences may seem large in the graph above, the numbers are not vastly different (the highest percentage difference is about 9%). You can see from the graph below, which has an X-axis which starts from zero, a more realistic impression of the differences. Examining the actual numbers, and the scale, is always important when making comparisons. Both graphs are based on exactly the same figures. Only the scale is different. You need to be careful about scale when making comparisons.

What similarities or differences are there between the populations of Sweden and Portugal?

To write a short description of this graph ask yourself (and answer!) the following questions:

1. What exactly does the graph show? (Use the chart title to help you answer this question)
2. What are the axes and what are the units?
3. What changed?
4. How much did it change?
5. What comparisons can you make between the two data series?

Answering these questions will help you to write a short description of this graph.

Here is an example:

This graph shows population change in Sweden and Portugal from 2013 to 2021. Sweden's population grew steadily from 9.6 million in 2013 to 10.4 million in 2021, an increase of 800,000 people.

By contrast, Portugal's population fell over the same period. The population declined steadily from 2013 to 1018 from 10.46 to 10.28 million, but from 2018 to 2019 the population remained stable. From 2019 to 2021 the population rose slightly to 10.33 million. Overall from 2013 to 2021 the population of Portugal declined.

While Sweden's population grew by 800,000, Portugal's fell slightly by 130,000, a decline of 1.243%. This means that in 2021 Sweden's population was greater than that of Portugal.

Signalling contrast

Two contrast signalling devices are used in this short description: "By contrast" and "While". Others are "on contrast", "on the other hand", "whereas" "however". Contrast is also signalled by using the comparative form of adjectives. For example: In 2013 Portugal's population was higher than Sweden's, whereas in 2021 it was slightly lower.

The follow authentic graphs feature comparisons: smoking linegraph, opioids linegraph, opioids2 linegraph, and new zealand smoking linegraph, along with explanations about their use.