1.6 Analysing data

Summary: How can we measure how human activity affects our planet? Collecting data and then plotting graphs helps scientists and others to clearly see any patterns or trends over time. Tags: science oxford-science student-book-7 Created: 2026-05-19 Last Updated: 2026-05-19

After this topic, you will be able to:

• identify patterns or trends in data using a graph or chart
• interpret data to draw conclusions.

Think back

1. What are the three main types of graph or chart used in science?
2. What type of graph is used to plot continuous data?
3. What is a prediction?

Key idea Scientists use their graph or chart to analyse data. A line of best fit helps show a pattern or trend. This shows how the independent variable affects the dependent variable. Scientists can then write a conclusion.

Key words analyse, pattern, trend, line of best fit, conclusion

How can we measure how human activity affects our planet? Collecting data and then plotting graphs helps scientists and others to clearly see any patterns or trends over time.

Identifying a pattern or trend

When you analyse your data, plotting a line graph or chart helps you to spot a pattern or trend. It shows how the dependent variable is affected by the independent variable. For example, the bar chart in Figure 1 shows that the Amazon rainforest is getting smaller over time.

Figure 1A bar chart showing how the size of the Amazon rainforest has changed over time. Full text alternative to the content

To make the trend easier to see on a graph, you should add a line of best fit. This is a straight line or smooth curve (bend) that goes through, or very close to, as many points as possible. There should be equal numbers of points above and below the line. If there are any anomalies, you should ignore these when you draw your line of best fit.

What does a line of best fit show?

The line of best fit tells you about the trend in the data.

• If the line slopes up, like in Figure 2, it means that as the independent variable increases, the dependent variable increases too.
• If the line slopes down, like in Figure 3, it means that as the independent variable increases, the dependent variable decreases.
• If the line is horizontal, like in Figure 4, it means that as the independent variable increases, the dependent variable does not change.

Figure 2As the independent variable increases, the dependent variable increases. Full text alternative to the content

Figure 3As the independent variable increases, the dependent variable decreases. Full text alternative to the content

Figure 4As the independent variable increases, the dependent variable does not change. Full text alternative to the content

Look at the line graph in Figure 5. Katie and Rahim added a line of best fit to show how temperature affects how high a ball bounces.

Figure 5As the temperature of the tennis ball increases, the mean bounce height also increases. Full text alternative to the content

The line is sloping up. This means that as the independent variable (temperature) increases, the dependent variable (bounce height) increases as well. The trend can be written as: As the temperature increases, the bounce height also increases.

A State the trend shown in Figure 1.

Writing a conclusion

Once you have analysed your graph, you can write a conclusion. This is where you write down what you have found out. Start by describing the pattern in your data, or the relationship you can see between the two variables in your graph or chart. Katie writes:

When the ball is warmer, the ball bounces higher.

Saying what your results show is only part of analysing results. You also need to use scientific knowledge to explain the pattern or trend.

Rahim begins to explain the relationship between temperature and the height of the bounce:

The ball bounces higher when it is warmer because the ball is softer.

However, to come up with a good explanation, he needs to understand why balls bounce. You may want to do some research to help you explain why something has happened.

Finally, you can compare your results with your prediction.

B Katie predicted that if the ball was hotter, it would bounce higher. State whether or not Katie’s prediction was correct.

Stretch zone

1. Copy and complete the sentences. To analyse your data, you plot a graph and work out the relationship between the predictions/variables. Then you write a conclusion/prediction that includes what you have found out, and explains why. Finally, you compare your results with your conclusion/prediction.

Stretch zone

1. A student plots a line graph showing how much time it takes sugar to dissolve in different water temperatures. Full text alternative to the content Explain why they plotted a line of best fit.Use the line graph to describe what happens when water temperature increases.